Fish school size

[Mental_Butterfly]

How do they determine the "right" minimum size for a school of aquarium fish? For example, people usually say a given tetra species should be kept in groups of at least 5 - How do they determine that that's the best minimum number? Are there studies out there on the comfort levels of fish in groups of, say, three versus five versus seven? Last time I checked fish couldn't count, will a group of four fish really be that adversely affected?

By the way, I'm just asking this out of intellectual curiosity, not because I want to try adocating the keeping of only one neon tetra or some madness like that.

 

[misterking]

I'd have thought it's been worked out by experience. In the wild, the vast majority of tetras, barbs, rainbowfishes, danios, rasboras etc etc typically shoal in large numbers for security. I don't think it'll be a case of fish can count, but I think that the fish can see it's in a larger group and will feel more secure, leading to a happier fish which eats better and has better colouring. Also, for fin-nipping species, keeping them in an even shoal of 6 or more helps to spread aggression throughout the group rather than it being focussed on one single fish so in an aquarium where a single fish can't escape the aggression, it serves a practical purpose too.

btw, I like the names of your fish

 

[homebunnyj]

You can make your own observations. You can see a real difference in fish behavior depending on the number of fish in the school. It does vary. I find that with black skirt tetras, a good number is at least ten... otherwise they pick at everyone else in the tank. Even with ten they look raggedy from picking on each other. (I have an aversion to them now, they were an annoyance to me no matter how many of them I had. I'll not have them again.)

 

[misterking]

I had the same problem with my first lot of black skirts.. but my second lot never fin-nipped, even with angels, they were in a group of 10.

 

[MissFishy]

For some reason the schools always look better with odd numbers as well, just another one of those weird things...

 

[Mental_Butterfly]

For some reason the schools always look better with odd numbers as well, just another one of those weird things...

You know, I've noticed that, too.

Thanks for all the answers, I guess it all boils down to common sense and observation. It was just one of those things that you see repeated everywhere but no one ever seems to explain why.