Catfishes: Getting by in schools, shoals, and with the comfort of friends!

If you're like me, you love sizable shoals or schools of small fishes in large tanks. 

And you probably have kept many schools of characins and such. You KNOW that most of these fishes simply fail to thrive when not kept in schools.

When we started Tannin LIve!, I felt that it was important to offer fishes in groups, as opposed to "singles"-to help facilitate the beneficial aspects of this social behavior.

Oh, but first, a refresher of sorts...The word "fish” is the correct plural form when you’re referring to a group of specimens all belonging to the same species. “Fishes,” on the other hand, refers to a group which consists of more than one species.

Now, let's just jump on that most confusing of fishy distinctions...the difference between a shoal of fishes and a school of fishes:

A shoal is a group of fish congregating together, perhaps even to benefit from the safety in numbers...yet not moving or behaving in unison. They can be facing in multiple directions, with no coordinated actions. That's the distinction.

A school is when all of the members of the group are moving and behaving in a coordinated manner. 

Personally, I've always liked the idea of keeping groups of the same species together whenever possible- regardless of if they school together, or simply "cohabit."

Okay, all of that grammatical B.S. now safely felt with and tucked away neatly, let's think about the idea of keeping lots of fish- or fishes- together in our tanks!  Some of the best fishes to keep as single-species schools, in my opinion, are catfishes, like the Corydoras, Brochus, and even the Otocinculus species.

The dynamic of keeping these endearing fish in groups is almost irresistible...and mimics how they are often found in nature. They are really social fish!

Not only do the fish show their most interesting behaviors in single-species groups, they seem to feed better, stay healthier, and spawn more easily, in my experience. I recall that I had a sizable group of 14 C. panda a while back in one of my aquariums that lived very well together in a school that I gradually built up. However, they  actually seemed to behave more shy- or perhaps you could say, "cautious"-as a big group than they were as individuals or small groups.

I would say that they definitely "schooled", but they adapted a strange "schedule" once the group truly became a school, and they were almost nocturnal or crepuscular, often coming out as a school, seemingly from out of nowhere, just as "dusk" broke in my tank (gotta love controllable LED's, huh?)! Of course, if you dropped in food at almost any time of the day, all bets were off, and they came out to feed actively- and then quickly went back to wherever the hell they hid during the day..

And then there are those Otocinculus...

This is a fish that just seems to be, well- problematic- for many...And I think it's no secret that they often suffer from 1) Lack of sufficient algal growth, and 2) The apparent "comfort" of the company of their own kind. They will often live for what seems like extended periods of time in a solitary manner, or even in small groups- only to just sort of "fade" at some point.

Personally, I think that this fish creates a sort of "paradox" for aquarists: One one hand, you want to support it's need for socialization by keeping it in larger groups (say, a minimum of 6-8 specimens), while on the other hand, providing sufficient micro algae growth on rocks, plants, and other aquariums surfaces. I wouldn't even think of keeping this fish in groups of less than 6 individuals...again, possibly problematic if you're tank can't provide sufficient algal growth for them.

Yeah. Paradox.

And of course, everyone knows that some species simply need to be kept in groups to confidently exist in your aquarium. For example, the Glass Catfish, Kryptopterus sp. is a fish that will literally waste away when kept individually, like so many of us probably did when we were kids.

These are fishes that truly have a timid and non-aggressive nature, and they should always be kept in a group...and by "group", I'm thinking 6 or more...even larger, if your tank can accommodate them.

(Pic by JohnstonDJ, used under CC BY-S.A. 2.0)

And, if you're curious to see how these fish can act in a large group, check out Tai Strietman's video of his Asian-themed tank. They display a relaxed, gregarious nature, which is much more natural than the skulking, timid personality they display when kept individually. It's plainly obvious, when you watch this video, that these fishes are near-perfect to keep in this fashion, and you'll never keep them individually again! 

You probably have already considered this idea of keeping various species of catfishes in groups, but it's something I felt like touching on because I still see many hobbyists keeping them individually or in very small groups, which is a bit surprising. Regardless, in this era where tanks are set up as a temporary display, or set up to highlight the aquascape, with the fishes simply being "accessories", we often see tanks with the fishes installed without due consideration for their long-term need. 

It need not be this way. In fact, it shouldn't be this way.

I'd go so far to suggest that, even if you're setting up a temporary display for a competition, or whatever, you need to display them in proper groups. Remember, a display seen by a lot of people who might be influenced by it should be set up with animals in proper context.

A simple concept. Probably almost "remedial" in nature. However, something that we need to keep in the front of our mind when setting up our next aquarium, no matter how unique or different it may be. Place the needs of your fishes first. 

You probably know that. So,please  pass along the thought to someone who might not.

Stay considerate. Stay supportive. Stay inspirational. Stay devoted.

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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