Im thinking of buying some new fish for our existing tank and wondering what the best advice is.

I think our tank is 64l and weve had it over three years. We havent added any fish in a while and would like to put a few more in.

The internet seems to suggest you should only add one or two at a time but im looking for neon tetras to add to the ones we have which i thought you were best to add in groups.

Ideally id like to add about 5 neon tetras and one or two platties. That seems like too many to add in one go but would it be ok to add tetras then next time round add platties?

At the minute i would say we have room for more. We used to have more fish but as theyve died we havent replaced them. My tank isnt overcrowded but i dont want to add too many at once.

What is the current stock you have in the tank first?

We have 5 neon tetras (there were more as i think they prefer to be in shoals), 4 platties, a swordtail and a mollie.

Theres also a bristlenose plec or something like that, and a golden coloured little loach thing. Both of them are fully grown and are quite small.

We used to have more as we had guppies when we first started but they died out.

Ok, that sounds fine! However, would you be ok only adding maybe 2-3 more tetras and skipping the platties? I know the tank probably looks like it has more room for more fish, but when you add more you increase the bioload (waste) in the tank, and that could cause ammonia problems down the line and could really harm your fish.

If you're really set on getting another platy, you COULD add only 1 more, but I'd say that's about the max fish you could have in a 64l tank.

Hope my advice helps.

Yeah thats fine. Thanks for the advice,

I know neon tetras like big groups but its hard to know how many is too many to add at a time, especially when some shops sell them in groups of 5.

Yeah, they normally recommend no less than 5 as they're quite social fish.