reexamining schooling / shoaling fish, by tank size…

[Magnum Man63 178]

so, we all know some fish are listed as best kept in a school of “X” amount of fish, which is often frustrating, as our schools never stay at that perfect / minimum number, and I have several schooling fish, that I refer to as long timers, who being 1 or 2, have outlasted one or more restockings of their species of schools, why those 1-2 fish continue to live on, while the dozens of replacements dwindle warrants some understanding…

I personally think an amount of personal space, territory, or ideal habitat better determines how many of a species will thrive in our tanks… in the wild, with seemingly unlimited space, we may witness schools of 100’s or 1,000’s, yet in our “jails” that perfect number may end up being 1 or 2…

for me, a nice size tank is the standard 55 gallon, I do have smaller tanks, but those end up being specialty tanks, and typically are not used to maintain a school of fish, yet, even a 55 gallon tank, will not sustain what is often listed as minimum numbers of some fish, and I end up with a few long timers… the long timers confirm to me, that the water conditions are at least ok, for maintaining long life but there is just something that is not acceptable for a minimum listed school for many fish…

I have the hardest time maintaining school sizes of several tetras , and cousins I love cardinal tetras, and have one long timer, that has survived through 3 schools of a dozen…

I have marble hatchets who I was watching this morning, and gave me the idea… I started with a recommended school size group, and have 2 long timers who each prefer one little spot in the surface roots of terrestrial plants…. I was thinking these micro choice spots in the tank may not support a whole school of hatchets like a larger area in the wild???

thoughts on keeping schooling fish long term, in aquariums???

 

[GaryE24 22]

The biological definition of schooling is when fish swim together in a coordinated fashion, moving together and gaining a streamlining advantage from coordinated movement. Schooling is often a lifetime strategy.
Shoaling is when fish group together for social reasons, and don't coordinate their movements beyond a general movement in a direction. There's none of that everyone turning on a dime, and groups break up.

Shoaling is what we get in aquariums, sometimes. It's more like herd or pack behaviour to me.

It can only happen in tanks that are way larger than the fish in them. Without being able to build up a head of steam, I don't think we can expect fish to truly shoal in captivity. In those public aquarium tanks where we stand tiny in relation to the structure, I've seen it. I've even seen schooling.

In a tank, shoaling becomes social behaviour and can be replaced by other social activity. I've noticed the species that do this want to keep an eye on each other. If they see things going well while they forage, they don't need to coordinate. With no threats and glass walls stopping them from building momentum, they get stopped.

I don't keep shoaling fish, as a personal rule, in tanks less than 8 to 10 times their total adult length. That cuts me out of keeping a lot of fish. Even a 2 inch fish that naturally shoals, like a rummy nose tetra, won't shoal as much in a tank of only 48 inches across. How can they. The glass walls are real obstacles to the behaviour.

I have one species here, Bathyaethiops greeni, that really wants to shoal. 4 years in, I have lost 2 out of 8. Plus I think they've learned that as 2.5 inch fish in a safe 6 foot tank, why bother? They don't need a defensive group. They can see each other easily, even across the tank. I find the tight behaviour they arrived from the wild with is diminishing with time.

 

[gwand62 179]

My B. brigittae shoal daily. Especially around meal time. There are about 30 of them in a ten gallon tank.

 

[Jennet42 100]

My few also shoal in my 21 gallon at mealtime, but also at other times, as well as playing in the flow of water at the top.

 

[Back in the fold17 2]

Schooling shoaling , it’s just fish swimming together to me . I know there’s a difference as Gary noted but it doesn’t matter to me .
Now . . . . . how to keep that group together ? Fish croak , fact of aquarium keeping . I think a guy just has to keep replacing the fallen . Replace them immediately as it happens and don’t put it off .

 

[GaryE24 22]

I'd forgotten about the tiny Bororas. They do shoal, but even a 10 gallon looks large relative to their sizes. I had a bunch in a 20 gallon when I first moved, and they were able to make a world of that single species tank. They bred in there, increased their shoal size - wonderful little fish.

To do the same with some larger species should be possible, but you'd need a huge tank.

We develop these magic minimum numbers, and Byron had found a paper on fish behaviour that suggested ten was the basic number to begin to see more natural behaviour from the shoalers studied. I take that to mean you need 20 of such a fish to start, but that's an investment in space and money not everyone can manage these days.

I find that in this new world of online buying and shipping, fish losses are up. I like the broad group that used to be corydoras, and when I get them shipped, it seems I always lose a couple during QT. One of the shippers I use does it right, single packing them, but the other insists on bagging them together and while he has excellent species choices and great fish in his faraway store, I have to buy a dozen to be sure of a good group. Fish take a beating in shipping, even more so now that's getting cold.