Does odd number really matter for schooling fish?

[wsuuwp]

I have been told many times you need to purchase odd numbers for schooling fish. I have done this every time I have purchased schooling fish (Salt: fire gobies, chromis, anthias; fresh: rasporas, tetras). In all cases, my stocking dwindled to an even number (4, 2) or down to 1 fish. I have never seen odd numbers seem to matter. Just curious, does anyone have instances where this mattered?

 

[Jay Hemdal Verified Community Expert]

I have been told many times you need to purchase odd numbers for schooling fish. I have done this every time I have purchased schooling fish (Salt: fire gobies, chromis, anthias; fresh: rasporas, tetras). In all cases, my stocking dwindled to an even number (4, 2) or down to 1 fish. I have never seen odd numbers seem to matter. Just curious, does anyone have instances where this mattered?

Welcome to Reef2Reef!

I've never heard the "odd number" thing. Commonly, pet stores will tell you that certain fish need to be kept in groups, the number they give is usually 5, but sometimes 3.

Having small groups of fish is done for two reasons - to build the schooling behavior (usually 5 or more fish) or to deflect aggression (3 or more). Still, that doesn't always help - green chromis for example will school in the wild, but in aquariums, they often pick on the smaller, weaker members of their group. Anthias schools often change dynamics as fish turn into males and fight more.

Then, there are actually two different terms; schooling and shoaling. Schooling fish form strong bonds and use that to travel in safety. Shoals are looser assemblages of fish that just sort of "hang out" together. They can even be different species. Most marine aquarium fish form shoals.

 

[Randy Holmes-Farley Verified Community Expert]

Welcome to Reef2Reef!

I've never heard the "odd number" thing. Commonly, pet stores will tell you that certain fish need to be kept in groups, the number they give is usually 5, but sometimes 3.

Having small groups of fish is done for two reasons - to build the schooling behavior (usually 5 or more fish) or to deflect aggression (3 or more). Still, that doesn't always help - green chromis for example will school in the wild, but in aquariums, they often pick on the smaller, weaker members of their group. Anthias schools often change dynamics as fish turn into males and fight more.

Then, there are actually two different terms; schooling and shoaling. Schooling fish form strong bonds and use that to travel in safety. Shoals are looser assemblages of fish that just sort of "hang out" together. They can even be different species. Most marine aquarium fish form shoals.

Hi Jay,

Any comment on yellow tangs (small group of them) in the context of shoaling in a reef tank, as opposed to constantly fighting?

 

[Jay Hemdal Verified Community Expert]

Hi Jay,

Any comment on yellow tangs (small group of them) in the context of shoaling in a reef tank, as opposed to constantly fighting?

Sorry, no. That’s one species that I superstitiously go with just one per tank for home sized aquariums. In our large reef exhibit, we put 50 in there with no fighting at all. I’ve seen pictures of people’s home tanks with small groups of YT doing fine.
I think adding them all at one time could be helpful.

 

[Randy Holmes-Farley Verified Community Expert]

Sorry, no. That’s one species that I superstitiously go with just one per tank for home sized aquariums. In our large reef exhibit, we put 50 in there with no fighting at all. I’ve seen pictures of people’s home tanks with small groups of YT doing fine.
I think adding them all at one time could be helpful.

Thanks, Jay. :)