Friday, 30 November 2007


Last week, I lost three of my cherry red shrimp, perhaps as a consequence of a large swing in temperature. I still have one of the original adults (a male, presumably) and at least a dozen juveniles (the largest of which are almost the size of the male).

Over the last few days I have been seeing some tiny organisms swimming around in the tank. Initially they were just at the limits of my perception, but by today they approaching a half a millimetre. Are they some sort of small crustaceans which were introduced with the plants but are finally reaching population sizes that allow them to be noticed, or are the baby shrimp? It's possible that one of the females was carrying eggs that hatched before she died - but I'm surprised that I would have missed something like that. Of course, it's also possible that one of them was carrying eggs when she died - and that some of those eggs managed to survive untended.

I suppose I shall find out eventually whether these are shrimp or something else. Shrimp would be cool. A spontaneous Daphnia population would also be kinda cool.

Aquascaping, part IV

One of the common complaints about aquarium plants is that, as they grow taller, they lose their lower leaves. This is especially true in lower light situations. Most people will recommend trimming the plants, removing the bases and replanting the tops. In a mature, heavily-planted aquarium that's probably the right idea. But when you are trying to grow a stock of plants, it isn't the best idea - in that case, the objective is to maximise your stock of planting material.

When you prune a plant, it will normally produce new shoots from an existing axillary bud. These buds are located at the point where the petiole of a leave joins the stem (or where one used to be before the leaf was shed). When a stem it pruned, one or more axillary bids start to grow. This can produce a bushier plant, but the appearance isn't always what you would want, since you end up with a distinctly smaller shoot coming off of a larger stem.

If the branch develops from the topmost axillary bud, there's a chance that it will develop into a new leading stem. But will that really create the desired look? This is far more important for foreground plants than it is for background plants, of course. From this perspective, it seems like it would make sense to cut plants back are low as possible, leaving an almost indistinguishable old stem. The obvious problem there is the danger of cutting it back too far. The plant can only produce new stem material if it has the resources to do so. How little is enough? That's not only going to vary from species to species, it's also going to vary from individual to individual. A small scrap of Java fern leaf will grow into a new plant, but how little Ludwigia stem (to use the example in these pictures) will produce a new plant?

There is, of course, another problem as well. Large, healthy plants do not appear out of nowhere. If you prune too heavily you may end up with a large stock of skinny, sad-looking plants.

Thursday, 29 November 2007

Aquascaping, part III

Adding rocks created a little more dimension to my tank, but it still wasn't enough. Around the same time I set up the plant tank (or perhaps it would be better to call it a plant nursery, since that is how I originally envisioned it) and purchased a few more plants. Perhaps it was serendipity, but I got some new Cabomba and Water wisteria (Hygrophilia difformis), together with some new Ludwigia. Without high-grade lighting and CO2 injection, I am not going to be able to establish the sort of super-dense garden tanks that are so popular these days. I shouldn't be trying to mimic those setups - I need to work on producing the best aquascape I can, given my constraints. But I can still learn from them without resorting to a crude caricature, a child's imitation.

Although it didn't start well, I have been very happy with Cabomba. Initially it became very stringy, elongating its internodes in a push for the surface of the water. But now, it has thickened up pretty well and filled out. But trimming and replanting the tops, I have the makings of a nice little Cabomba forest. The cut stems have resprouted, and a few uncut stems have also sprouted. While it doesn't seem to match well with modern ideas about aquascaping, it has a "natural" feel to me, the feel of a macrophyte-filled lake. The water wisteria were planted in an area behind the driftwood, adjacent to the smaller of the Echinodorus. The divided leaves emerge from an area dominated by shorter plants with narrow, elongate leaves. I like the effect, but it's a little asymmetrical.

I recently read an article about Dutch aquascaping. While the practice stresses garden-like layout and terraced arrangement isn't something I plan to implement, I was struck by the idea of using "pathways" to create an illusion of depth. I really think that's something I could make use of.

Monday, 26 November 2007

Dietary preferences

It's interesting to see how fish differ in their dietary preferences. I bought some frozen Tubifex worms a few weeks ago, and offered them to my fish. The occupants of the Macropodus tank immediately went crazy over the stuff. On the other hand, in the main tank no one but the Panda corys and the neon tetras showed much interest in it initially. Over time most of the other fish have learned that this is food, but only the pandas would go after it when anything else is present - and the Macropodus still don't realise that Tubifex worms are food. It's odd, given that their siblings are the ones that are most eager to eat it.

I noticed that the leaves of the 'Water wisteria' (Hygrophilia difformis) in the Macropodus tank have been chewed on, so I decided to see how they would respond to blanched spinach. Again, unlike their siblings in the main tank, they went after it enthusiastically. So finally, I offered them blanched zucchini. Twelve hours later it sits untouched at the bottom of the tank. I also added some zucchini to the main tank for the Otocinclus. Much to my surprise, one Macropodus and one cory took a liking to zucchini.

I find it interesting the way that dietary preferences differ both among individuals and within the "culture" of a tank. The Macropodus in the main tank and those in the Macropodus tank are "littermates" and full siblings. And yet they differ in terms of their willingness to take food items. Competition for food is more intense in the Macropodus tank, so it isn't surprising that they would more readily take any food item offered. But why do their siblings in the main tank totally ignore the same food item? The zucchini issue shows another level - that of "personal" food preference.

While I added zucchini primarily for the Otocinclus, the only other fish I have seen eating from it was one of the kuhli loaches.

Saturday, 24 November 2007

Shrimp mortality

I found two of my cherry red shrimp dead today. While I'm sadden by their deaths, I am more concerned by the fact that I don't know what killed them. Was it just chance? I doubt it - one death at random wouldn't surprise me, but two seems to be a bit much of a coincidence. My water parameters seem to be ok. The only real notable change is the weather - temperatures fell from about 27°C/80°F on Monday to about -3°C/27°F on Tuesday night. While I have a heater on the plant tank, it lacks a cover (and the cat pushed the shade away from the window, which probably exposed the tank to draughts).

So is it the weather, water quality, a pathogen, or just coincidence? I wish I knew.

Main tank

Aquascaping, part II

Over the course of the next few months I added a few plants - most notably a couple Spathiphyllum plants - not true aquatics (although I didn't know that when I bought them), but they can survive for extended periods underwater - and a couple more Echinodorus. The Spathiphyllum anchored the back right corner of the tank, while the new Echinodorus plants occupied spaces on either side of the filter intake.

Echinodorus, the "Amazon swords" are an interesting - and diverse - group of plants. My original ones were a tall species - once they get large enough, they produce emergent leaves. They would make nice pond plants and would be good in open tanks, but they really aren't idea for the setup I have unless you are willing to do some major pruning. From what I have read, pruning the roots is probably the most efficient way to produce a smaller plant. The corys excavated the root ball of one of the large Echinodorus, which had the desired effect of dwarfing the plant (for the time being, anyway). I may trim the root mass again in a few months, or try dividing the plant. The other species of Echinodorus is very different - it's really the idea plant for my setup. It has shorter petioles and more lanceolate leaves. Ever since I switched to 6500 K plant bulbs it has produced smaller, denser leaves. It makes a good background plant, filling space at the back of the tank. Since the plants came with plantlets (flower spikes which had either failed to break the surface or, more probably, been submerged when the plants were prepared for shipping), I planted them in what became the Macropodus tank. They seem to have done well in that overgrown, badly overstocked tank. Since I upgraded the lighting in there (from the original incandescent bulbs to compact fluorescent) they seem to be doing better. Unfortunately, conditions in that tank favour algae growth (no snails, excess nitrates) so the leaves tend to have a lot of epiphylls (plants that grow on the leaves of other plants; in this case, algae). During that period I also received a number of plants from a friend. That increased my species diversity, and gave me some new options. I also bought a piece of driftwood. Eschewing the normal rules, I placed it to the from of the tank where it provided cover for my kuhli loaches in a place where they would be visible to me.

Unfortunately, I also suffered an ich outbreak. Since I was unwilling to use any of the commercially available ich treatments (most are based on malachite green, a carcinogen), I decided to go with high temperature + salt. While this succeeded in clearing up the ich problem, it also wreaked havoc on the plants. The entire experience dampened by enthusiasm, and the issue of aquascaping was put on the back burner.

Things changed again late in the summer. As is customary, we went Petosky stone hunting when we were in Michigan, and walking along the pebble beaches I collected a number of other interesting rocks. When I got home I gave some of them a shot in my aquarium. I wasn't sure about their suitability - if they were carbonate based they would probably raise the hardness significantly - but I thought it was worth a shot. I excluded the glittery rocks out of concern that they might contain pyrites (which could yield suphuric acid in the tank) and the Petoskies (pretty, but I knew them to be calcite). I figured I could take them out if they increased the hardness too much.

Adding the rocks changed the tank substantially for the corys. Prior to that, their use of space was largely governed by the availability of cover. Large, open areas to the front of the tank were rarely used during the day. Adding rocks along the bottom of the tank creased more usable space for the bottom-dweller. Coupled with additional substrate in the back left corner of the tank, there was the beginning of an aquascape. Since then I have added a few more plants. Establishment of the plant tank also created a source of cuttings that I could use in the main tank. Unfortunately, the first species I focussed on proved to be a poor choice.

Aquascaping, part I

When I first set up my tank, I was interested in having plants, but I had no real concept of "aquascaping". There was only a limited selection of plants, and I didn't have any idea of how densely I should plant the tank. In a certain sense I was lucky - I didn't waste money planting a dense garden which would have promptly died through lack of light and carbon dioxide.

My initial setup was deficient in more ways than I really want to discuss. The Echinodorus plants were a good focal point on one end of the tank. Since they were sold singly it was pretty easy to plant them properly. The Java ferns were, similarly, easy enough to separate, although I didn't know that you were supposed to keep the rhizome above the substrate. Even more problematically, I had no idea that I should separate the bunched plants. Had I separated the Ludwigia, Bacopa and Myriophylum I would have had a more garden-like arrangement, and may well have had better survival rates. Other problems included the total lack of non-plant features on the bottom of the tank and no real sense of what my ultimate design goal.

With no goal it was easy to end up headed nowhere.

Friday, 23 November 2007

The cave

This is one of my favourite features of my aquascape. It's a bit less impressive viewed at the level of the tank, but I still like the look.

It's probably pretty apparent that the Cabomba could use a bit more light. The microsword (Lilaeopsis brasiliensis) in the foreground was uprooted by the fish (probably the kuhli loaches) and I replaced it with some small Hygrophila polysperma (which I removed when I decided to eliminated the species from my tanks).

Wednesday, 21 November 2007


I counted at least a dozen baby cherry red shrimp yesterday. The largest of them is 11-12 mm long (plus tail).

And in the main tank, I have seen a ghost shrimp twice in the last couple days. That was quite a surprise - I didn't really think any had survived the initial introduction.

Tuesday, 20 November 2007

Photoperiod and plant growth

As I mentioned in my last post, conventional wisdom is that aquarium plants "can't use" light beyond a 10-14 hour photoperiod, and anything beyond that ends up going into algal growth. Explanations like that don't make sense to photosynthesis supposed to shut down at a certain point? But that doesn't mean that the observation isn't true (something this well established is likely to be based on fact), but I'm curious about the underlying mechanism.

In a 1998 paper, E.B. Jensen and B. Veierskov looked at the effect of photoperiod on photosynthesis in tomatoes. They found that increasing the length of the photoperiod from 8 hours to 16 hours caused the carbon dioxide assimilation rate (i.e., the rate of photosynthesis), but photosynthetic rates fell with a 23.5-hour photoperiod. (Open bars in the figures). Starch and sugar concentrations showed a similar pattern.

This is interesting - an increase (and then decrease) in the rate of photosynthesis. The paper provides a mechanism for this difference - changes in chlorophyll a, chlorophyll b and carotenoid levels probably explain these differences.

Protein levels increased sharply at a 23.5-hour photoperiod, as did ethylene production (ethylene is a plant hormone which is produced in response to stress). The transgenic pTOM13 plants (shaded bars) have a reduced ability to produce ethylene. Jensen and Veierskov concluded that ethylene production is likely to be the cause of the "chlorosis, leaf distortion, purpling of older leaves and growth reduction".

So what does this mean with regards to the original question of how long to leave the lights on in your aquarium? It's a start - the idea that overly long photoperiod can damage plants is reasonable. But you can't readily translate that into the specific requirements of even the most common aquarium plants. More importantly, saying that excessive day length harms plants isn't the same as saying that it encourages algal growth. While plant growth appears to suppress algal growth (or so says another piece of conventional wisdom), at this point it seems more likely that algal growth would either be an indirect effect (maybe increased nutrient availability driven by decreased plant growth?) or a direct effect unrelated to plant growth (for example, algal growth may increase continuously with photoperiod, while plant growth falls off once it exceeds some threshold, creating a relative advantage for algae).

I need to keep looking.
  1. Jensen, E.B. and B. Veierskov. 1998. Interaction between photoperiod, photosynthesis and ethylene formation in tomato plants (Lycopersicon esculentum cv. Ailsa Craig and ACC-oxidase antisense pTOM13. Physiologia Plantarum 103:363-368.

Monday, 19 November 2007


One of the bits of conventional wisdom that floats around aquarium articles and message boards is that tropical plants, which are adapted to a 10-14-hour photoperiod, and that anything beyond that is a bad idea. This article is a typical example:
Leaving the lights on 24 hours a day while you were away was not a good idea. Most of the plants we use in the aquarium come from tropical areas, and are adapted to about 10 and 14 hours each of day and night. At 2 to 3 watts per gallon of fluorescent light, a 12-hour photoperiod works well for me. This can be adjusted based on lighting intensity. In no case does it make sense to extend the photoperiod much beyond 14 hours. Most higher plants will stop photosynthesizing at this point, while the algae will take full advantage of this situation.
But is this really the case? Does photosynthesis shut down after 12 hours? Possible, but what's the source? I need to figure this out.

Equipment maintenance

Over time, I noticed that the water flow on my filters declined. In the case of the Macropodus tank, I wasn't too concerned - quite frankly, it's easier to ignore that tank than it is to stress about the fact that there are 40 fish I don't want (but don't know how to get rid up) taking up one of my tanks. Then I noticed that the biowheels on my main tank wouldn't turn. I cleaned the filters, I cleaned the intake, but nothing seemed to work. If anything, things got worse. Finally, I noticed the water flow decline on the plant tank. That started to bother me - the filter was only a few months old. Was the motor burning out already?

Finally, I decided to take it apart and clean it properly. Only when I took it apart, and then looked at the set-up and maintenance instructions, did I realise what the problem was. It was amazingly easy to do. The next day I did the same for the other tanks, and I was amazed at the water flow in the main tank. I had totally forgotten what it was like.

Of course, a few seconds on google could have told me that I needed to do that. Oh well...

On breeding corys

My fascination with corys dates to my childhood. I bought my first corys when I was 11 or 12. I had no idea what they were, but eventually I was able to match them to illustrations of Corydoras aeneus which, as it turns out, is native to Trinidad. After we moved the corys ended up as the sole denizens of their tank, alone and ignored. So it was much to my surprise that I found four or five of them swimming around in a tank where there had only been three. (And I use the word "tank" loosely - it was a very large old enameled pot that had once been used to boil diapers.)

Ever since, I have had a fascination with corys. They were among the first fish that I bought when I got back into fish keeping this year, and I now have five species of Corydoras. While I would be happy just collecting them, I have an urge to replicate what I once achieved through chance and neglect.

Most descriptions of corys mention spawning - this species is easy to spawn, that one is very difficult. In addition, they refer to the "classic" T configuration. Some people will even mention that the male forms the top of the T, and the female faces him. But I was never able to visualise it, and no one bothered to provide illustrations. Thankfully, I have finally come across an article with pictures. Ian Fuller's article So you want to breed corys? provides just that - a picture of the "classic T-position" (scroll down pretty much to the bottom of the page). On seeing that, my reaction was "oh, really?" Have I seen that before? I may have. It has a terribly commonplace look, the sort of thing I would not have identified as spawning behaviour. A while ago my first corys (species unknown) did a lot of what looked like spawning behaviour. I was looking for the T position, but never saw it (I was looking for something more dramatic). In my main tank eggs would probably be snail food and fry fish food. But it makes me hopeful that I could induce them to try a second time.

More pygmy corys

Having stripped about half the biomass out of my plant tank, I became reacquainted with the pygmy corys. I started out with ten in the tank; I'm not certain how many of them survived, but I'd say there's a minimum of nine. When they were first forced out into the open they became very skittish, but they seems to be settling down a little. So the thought of getting them to breed crossed my mind. Unlike Macropodus, I suspect there's a market for these fish - I have only seen them once at local pet stores. While I may not be able to sell them, I suspect I could get the one independent store to trade some.

I googled breeding pygmy corys and got several promising hits. While they all agreed that the fish weren't difficult to breed, they differed markedly with respect to their thoughts on the idea setup. Ian Fuller at Pets Parade ("Britain's Biggest Petshop") says he uses four males and two females for breeding. However, he is writing about all five "pygmy" species in the article (Corydoras cochui, C. gracilis, C. habrosus, C. hastatus, C. pygmaeus and C. xinguensis), so that may not be the place to look for something overly specific.

Writing at, Mike Hellweg gives a very detailed description of C. pygmaeus breeding behaviour. He notes that, although they spawn in a group, each male "stakes out" a specific female and breeds only with her. Consequently, he goes for balanced sex ratios in his breeding tanks. On the other extreme, Kaycy Ruffer at PlanetCatfish recommends "at least one female to six males".

There's a wealth of fish keeping advice online, but the problem is that people simply say what works for them. All three of these appear to have successfully spawned pygmy corys. None of them given any indication that they have experiments with different setups, and only Mike Hellweg explains why he made the decisions he made. It's like reading testimonials for "alternative medicine". Sure, people took the product and got result x, y or z. But how do you separate coincidence from successful practice? Therein lies the problem.

Irresponsible plant dealers

Almost every fish store I have been to sells non-aquatic plants as aquarium plants. In some cases the plants are non-aquatic, but can persist under water for months. If purchasers were warned, I could see a case being made for some plants (like Spathiphyllum, which is apparently good with very boisterous fish). It's irresponsible to see plants like that to unsuspecting aquarists. I was quite disheartened by my initial attempts at establishing plants (although salting the tank to deal with ich was probably the biggest plant killer).

It's one thing to sell your customers something that will never work. It's quite another to actually make them accomplices in lawbreaking. While I have not seen Hygrophila polysperma for sale in a fish store, it's available online. There are also reports that it is sold in pet stores. More disturbing is that fact that aquarium plant books published by reputable publishers say nothing of the fact that transporting the plant requires a permit, and possession in some states is a crime. Granted, there's no reason for a British publication to say anything about this unless they are producing an edition for the US market.

Saturday, 17 November 2007

Destroying the plant tank

I recently discovered the Hygrophila polysperma is listed as a federal noxious weed, making it illegal to transport without a license. It didn't occur to me to check state laws. Turns out, it appears to be illegal to possess the plant in Oklahoma. So, sadly, I decided to get rid of it.

In three of my tanks that isn't a huge deal - while it was in all of my tanks, it wasn't a major component of the flora. In the plant tank, on the other hand, it was clearly the dominant plant. When I established the tank I took a lot of small bits and planted them with the hope of getting good stems to establish elsewhere. So not only was there a lot of biomass, there were an awful lot of stems of the stuff. Removing them is not only traumatic to me, it's also hard on the fish. After living life well-hidden, they are not out in the open. And I have to start over on my planting ideas.

The other challenge, of course, is disposing of the stuff. Two options are not available - sending it down the drain or throwing it in the garbage. Luckily, it has never flowered, so I don't have the worry of killing seeds. Still, just to be on the safe side, I decided to microwave the plant material for five minutes, and then let it dry completely.I can't see how it would survive that. Now the next challenge - getting the "plant tank" back to the point where it deserves that name.

Update: The challenge, I think, isn't killing the plant, it's finding all the bits. The very characteristics that make Hygrophila polysperma a problem plant also make it hard to eradicate - it can sprout from small pieces of stems floating somewhere in the aquarium (or body of water).

Thursday, 15 November 2007

Betta Bulb update

As I mentioned previously I planted several "Betta Bulbs" in my tanks a few weeks ago. While I haven't seen any signs of life in either my main tank or the Macropodus tank, I noticed something new in my plant tank about a week ago. Today I noticed a flower spike that had broken the surface of the water, and this evening I noticed a second plant.

One of my first thoughts was that while the plant could easily be an Aponogeton, I had my doubts as to whether it was Aponogeton ulvaceus (as the packaging claimed) - which is probably a good thing. Aponogeton ulvaceus tends to be a very large plant with broad, wavy leaves that presumably resemble the alga Ulva. One online description says the leaves are 3-10 cm broad. These plants appear to have far narrower leaves - at most a centimetre broad - but that might change as the plants get bigger. Perhaps the flowers will give me a better sense of what species I actually have, although there is mention of widespread hybrid origin of cultivated plants.

Sunday, 11 November 2007

Hygrophila polysperma - a noxious weed

In writing the previous post, I realised that Hygrophila polysperma is on the Federal Noxious Weed List.

According to the Federal Noxious Weed Regulations:
(a) No person may move a Federal noxious weed into or through the United States, or interstate, unless:
(1) He or she obtains a permit for such movement in accordance with paragraphs (b) through (e) of this section; and
(2) The movement is consistent with the specific conditions contained in the permit.
(b) The Deputy Administrator will issue a written permit for the movement of a noxious weed into or through the United States, or interstate, if application is made for such movement and if the Deputy Administrator determines that such movement, under conditions specified in the permit, would not involve a danger of dissemination of the noxious weed in the United States, or interstate; otherwise such a permit will not be issued.
(c) All such permits issued shall contain in written form in the permit any conditions (other than those conditions specified in this part) under which the permit is to be granted, e.g. conditions with respect to shipment, storage, and destruction.
(d) If the permit is denied, the applicant shall be furnished the reasons therefor.
(e) The Deputy Administrator may revoke any outstanding permit issued under this section, and may deny future permit applications, if the Deputy Administrator determines that the issuee has failed to comply with any provision of the Act or this section, including conditions of any permit issued. Upon request, any permit holder will be afforded an opportunity for a hearing with respect to the merits or validity of any such revocation involving his or her permit.
While the realisation that I may well be harbouring a "noxious weed" was a bit of a shock, the real issue appears to be one of transporting the plant, and potentially releasing it into the wild. According to the University of Florida Center for Aquatic and Invasive Plants, H. polysperma is present in parts of southern Texas and most of Florida, and has been reported from Virginia.

It's really a shame. The fact sheet describes almost the perfect plant for most aquarists:
Stems brittle, easily fragmenting, easily developing new stands from rooted nodes of even small fragments (Les and Wunderlin 1981). Able to form dense monocultural stands with emersed stem tips from depths as great as 3 m (10 ft) or more (Hall and Vandiver 1990). Able to photosynthesize in lower light than most native submersed species (Spencer and Bowes 1984). Tends to grow more vigorously in flowing water (Van Dijk et al. 1986). Flowers in fall and winter, with a high percentage of seed set in Florida populations (Les and Wunderlin 1981).
It makes sense though. A plant that does everything an aquarist could hope for will, necessarily be a weedy species with pest potential. I need to make sure all plant bits I dispose of are dead. I generally do that anyway, not because I am conscientious but rather, because I tend to leave trimmings sit in a container for a few days before I dispose of them. In that time they dry out thoroughly. Now though, I need to make a bad habit into a rule.

Update: According to this discussion, possession in Oklahoma may be a crime. Sadly, I think it's time to get rid of all of it. Now to figure out how to do that safely.

Saturday, 10 November 2007

Tank #4

I decided to bring the 2-gallon hexagonal acrylic tank back into use. Although we thought about shrimp or African Dwarf Frogs (Hymenochirus curtipes), we ended up going with a fighter again.

The tank has an undergravel filter and a fairly coarse gravel base, so it really isn't a good candidate for a planted tank. Nonetheless, I decided to set it up that way. That allowed me to use my plant tank for the purpose I set it up in the first place - as a source of plant material for my other tanks. I took a small Echinodorus out of the Macropodus tank, but the rest of it came from the plant tank. I took a good bit of Ceratophyllum (Hornwort), though most of it ended up in the Macropodus tank, opening up a large space in the plant tank. I also cut back the large stem of Cabomba that have reached the water level and grown across much of the tank. I pulled out a rooted Ludwigia plant and took a couple cuttings of Hygrophila difformis (Water Wisteria) and Hygrophila polysperma, which is considered one of the easiest aquarium plants (and not surprisingly, apparently it's a noxious weed).

I'm hoping the plants will do well in the new tank. I'm more interested in how that trimming will affect the plants that remain in the plant tank.

Thursday, 8 November 2007

Baby shrimp

I saw at least one baby cherry red shrimp in the plant tank yesterday. It was pretty cool - about 3 mm long. It isn't ideal breeding habitat for them though - between the filter and the pygmy corys, I don't think the survival probabilities are too high. The tank is good overall - it's densely enough planted by now there would be adequate hiding spaced from anything but pygmy corys.

I'll see what the survival rates are like. Hopefully I have at least one male among the shrimp, and they'll breed again soon. It takes about 28 days, apparently, after the eggs are laid. We'll see what happens next.

Some thoughts on tank evolution

Posting the "before and after" pictures of my tank got me thinking about the importance of a few key elements. The biggests problem with the "before" shots isn't the lack of plant cover, it's the fairly uniform and boring layout of the sediment. If I were to do it again, I probably wouldn't go for black and white gravel, but I would definitely start things up with a lot more rocks and wood.

If you have one big open space, fish use the tank as one big open space. Adding plants in the back and sides can create smaller refuges, hiding spots, but that doesn't offer any additional options with respect to swimming. The fish can hide or the fish can swim. But that's about all. When I added the driftwood in the centre of the tank I created an up-front hiding space (without it I would probably never see the kuhli loaches), but it still doesn't change swimming options. A shy fish can dash from cover at the edge to cover at the centre, but it's still a dash. But scattering rocks across the bottom of the tank (and adding plants between the rocks) changed the usable space dramatically. Suddenly the bottom of the tank was usable to relatively shy fish. It certainly made some of the corys more active during the day. This fairly small change led to created a new microhabitat encompassing most of the bottom of the tank. It should have been obvious, but it wasn't.