Is this danius aggressive?!

[freddiethegreat]

This is probably a stupid question, but I am a novice.

I have a nano tank (35l), have prepared, treated, fishless cycled etc. Yesterday I put in two platys and a zebra danius, all seemed fine. This morning the danius seems to be chasing the other two around and now one platys is hiding behind the filter at the top and the other is among the ornaments at the bottom (it's quite a deep tank, more vertical than horizontal iyswim) and the danius is going round & round in the middle (triumphantly?!)

Anyway, is this ok, or is danius/platys a bad combination?

TIA

danios aren't usually aggressive in the right environment, but all fish can show aggression under stress. danios are shoaling fish so should be in a group of 6+. this helps prevent stress and also means that any aggressive behaviour is spread out. they also need a lot of space because they are active fish. your danio will never behave naturally because he is alone and your tank is too small.

similar problem with the platies- they should be in a group and in a bigger tank.

is there any chance you could take them back and swap them for a betta? your tank would be ok for a single male betta but it's really too small for anything else.

Hmmm. Ok, thank you EauRouge. I'll have to think about how to tackle that (ideally a bigger tank & friends for these guys & a beta for this tank, but realism says not . . .) For the moment everyone looks more relaxed. Can't different breeds keep each other company?

That's why so many people end up with more than one tank

They are not different breeds, they are different species. So it's not like keeping a chihuahua and a yorkie to keep each other company, it's more like keeping a giraffe and a zebra- they do have some things in common but they won't communicate with each other in the way that fish from the same.species will. If they are not kept in large enough groups then it can cause all kinds of behavioural problems and leave them vulnerable to disease.