Tuesday, 26 February 2008

Otocinclus notes

Otocinclus, the dwarf suckermouth catfish, is a very popular algae-eating catfish. The seventeen species of Otocinclus (often called Otos) are very popular for algae control. Unlike their large cousins, the Plecos, Otos remain small and are not boisterous enough to cause damage to plants. Although they are often purchased singly for algae control, Otos are social and should not be kept in groups of less than three. They are native to South America east of the Andes mountains, in streams that drain into the Amazon, Orinoco, Paraguay/Parana rivers, and in streams that drain into the Atlantic in southeastern Brazil. They are notably absent from the Guianas.

Otos are small - they range in size from 16.5 to 43.8 mm (0.6 to 1.7 inches), not counting the tail. Females are 10-20% larger than males, and have a broader body, especially when they are in breeding condition. [Read the rest of my post at HubPages.com]

Corydoras notes

With 150 formally described species, and perhaps more than a hundred undescribed species, the genus Corydoras offers great possibilities for fish keepers. All species are easy to keep, relatively undemanding fish with great personality. Many of them are readily bred. For the average fish keeper they are relegated to the "cleanup crew" and kept singly or in very small groups. Even under those conditions, they can be interesting fish. Kept in larger groups, they really shine and can become the focal point of a lively aquarium.

Corydoras are social fish - they should not be kept in groups of less than three. They appear to be happiest in groups of six or more. With the right selection of fish and appropriate aquascaping you can enjoy almost constant activity as they swim around a community tank. [Read the rest of my post at HubPages.com]

Snails in aquaria

Snails are nearly ubiquitous in freshwater aquaria. Aquarists vary in their attitude towards snails - many see them as a scourge that must be controlled, if not eliminated outright. Bulletin boards are full of questions about how to control snail populations. Snails are easily introduced on plants, rocks or other decorative items like driftwood. Most reproduce quickly and some, like Malaysian Trumpet Snails, quickly grow to the level of infestation. Some snails eat plants, and can damage aquarium plants. Some will eat eggs, even baby fish. And some play a role in the life cycle of fish pathogens.
Many aquarists seem snails in a more positive light. Snails consume algae and can keep glass and rocks clean. Snails consume dead plant parts and uneaten food that might otherwise decompose and foul the water. Trumpet snails burrow through the substrate and bring oxygen into these substrates.
Quite apart from this utilitarian view of snails, some aquarists see them as desirable pets, and may dedicate aquaria to certain species. Popular pets include Olive Nerita snails, Ramshorn snails and Apple snails (also known as Mystery snails). [Read the rest of my post at HubPages.com]

Pygmy corys

They say that pygmy corys (Corydoras pygmaeus) are easy to breed. That is, of course, a relative statement. "Easy" relative to what? But at this point, doing so is one of my primary goals.

In general, in order to breed corys you need frequent water changes coupled with a "conditioning" diet. They conditioning diet is a rich diet - often with a lot of live food, and essential fatty acids - that bring the fish into breeding condition. Water changes, on the other hand, mimic the beginning of the wet season, when streams and pools get an influx of fresh water. Fresh water, often cooler (although people have said that "cooler" is not important for pygmy corys).

The tank the corys are in is open-topped. As a result of this, evapouration rates are high. Over the last several months, this has meant that I am more inclined to add water than I am to exchange water. Presumably that resulted in very hard water - not the optimum for these fish. So over the past few weeks I concentrated on getting the water closer to tap water, but doing frequent, large water changes. Over the last week I have tried to soften the water some more by adding reverse osmosis water.

The pygmy corys have responded fairly well to the water changes - they seem much more active the past few days, although they still spend most of their time hidden below the dense lawn of Hemianthus. I'm cautiously optimistic.

Sunday, 24 February 2008

Otocinclus tank

It's been almost a month since I re-did the former Macropodus tank. After I cleaned the tank out and added some new plants, the old plants died back seriously. It was especially noticeable with the Echinodorus, which had previously dominated the tank. Their leaves first went pale, and then much of the tissue died, but not the whole leaf.

Apart from adding a lot more plants, I also created a small "sand lens" in the front of the tank. And, of course, I added a population of Otocinclus and two dwarf corys. So how have things changed?

Here's the tank today; while I'm having a hard time getting the Lilaeopsis to root, the Hemianthis is really coming along nicely.

Here's the tank three weeks ago, when the die-back had just started

And here's the tank three days before that, shortly after I had cleaned it out

Monday, 11 February 2008

Using biogeography to guess at species identity

Just over a week ago, I found two Corydoras habrosus mixed in with the Otocinclus at the local Petsmart. Since C. habrosus is restricted to the Amazon basin, it struck me as a useful clue in trying to identify the Otos. In his 1993 monograph on the genus Otocinclus, Scott Schaeffer mentions that only two species of Otocinclus are found in the Orinoco basin - O. vittatus and O. huaorani. I'm leaning a little more towards O. vittatus, but I really need to take a better look at them.

Friday, 8 February 2008

Shape or colour? It depends on where you grew up

Dave Munger at Cognitive Daily reports on a study of how the environment in which fish are raised affects their spatial perception and memory. Convict cichlids raised in square tanks used shape and colour to navigate, while ones raised in round tanks relied on colour more than shape.

Thursday, 7 February 2008

Diversity in Malawi cichlids

Ed Yong has an excellent discussion of the way in which male aggression contributes to species diversity in Lake Malawi cichlids. While a number of factors were involved in the rise of this species flock, the tendency for males to be more aggressive towards males that look like them is likely to be one of the factors that drives speciation.

Wednesday, 6 February 2008


Judging by the Google searches that bring them here, a lot of people who find there way here are looking for the answer to a specific question...answers that my posts often don't provide. If you have questions - feel free to ask. I can't make and promises, but I'll give you the best answer I can.

Sunday, 3 February 2008

Otocinclus tank

While many aquarists value Otocinclus catfish as algae eaters, they seems to be looked on more as a part of the tank maintenance system than as "pet fish". And quite frankly, my impression of them was that they just weren't the most exciting fish. While I found them interesting, they never seemed to do much. So I was intrigued by an article in the February issue of Tropical Fish Hobbyist by Gary MacDonald. Not only did he say that they are very social fish, he also spoke of interesting dominance hierarchies in groups of 12 or more. While this caught my attention, I didn't feel like I had room for another dozen or so fish in my main tank. With the former Macropodus tank available, I ended up buying some, pretty much on a whim.

From what I've read, one of the major concerns about pet store Otocinclus is that they are often starving - they are herbivores, and are likely not to have had enough to eat for a while. There is also the stress involved in being caught and transported home. Once I got them into their tank, they all went for the bottom or the sides of the tank and just suck there. But after a few hours they were extremely active, swimming all around the tank, presumably examining surfaces for algae. They have slowed down a little since then, but they remain much more active that any Otocinclus I have seen previously. Of course, they are also very young - I wouldn't be surprised is they slowed down a lot as they matured. It'll be interesting to see what happens.

The great cory hunt

After finding a pair of Corydoras habrosus at a local Petsmart, I saw this post at PlanetCatfish - the poster had received a C. habrosus in a group of Otocinclus, presumably in Missouri. That got me thinking - since all the local Petsmarts presumably get their fish from the same source, maybe there were more C. habrosus at other local Petsmarts. So we decided to go on a cory hunt. We visited four of the seven Petsmart stores in the Oklahoma City metro.

We failed to find any more C. habrosus, but it was fun to try.

Tank shots

In the past couple days I added more plants to the tank, trying to create something of a thought-out aquascape (or at least something that could be thought of as something like a thought-out aquascape. Here's how it looked three days agoI added Hemianthis, Lilaeopsis and some Vallisneria to the forground, and planted a number of stems of Cabomba along the back, in front of the heater. I also added some Ludwigia along the centre, to add some more dimension. This is the way it looks now

New fish

For no reason in particular, I visited our local Petsmart today, and was rewarded with a rare treat - in a tank of Otocinclus there were two dwarf corys - not pygmaeus, but I knew it must by one of the others. It turned out to be Corydoras habrosus, a Venezuelan species.

That pretty much decided the fate of the former Macropodus tank. I couldn't put the new corys into the main tank (they're a bit small to cohabitate with adult Macropodus), and I didn't want to add them to the plant tank without quarantining them first. So that left the former Macropodus tank. And since I didn't want to leave them as the sole occupants of the tank, I took the opportunity to buy a dozen Otocinclus, as Gary had recommended.