Hi, I currently have 4 zebra danios and 3 white clouds in a 65l tank which i'm working on slowly building up to schools of 5 or 6 of each. Following this I'd really like to add a similar sized schoool of pretty little harlequin rasbora but I was wondering if this was too many small schools of fish for this size of tank? Would they all end up competing for the same tank space?

I think 6 of each of the existing is probably enough, though testing how fast nitrate rises will help.

But the other issue is temperature. The White Clouds and Danios are temperate whereas the Harlequins are true tropicals and it's not really possible to get a temp that all will be comfortable with. Max for your existing fish is 22C and min for Harlequins is 21C up to 28C max. No-one's going to be really happy at 21 or 22 unfortunately.

HTH

Dianos need 22c?

Just checked Caresheet details and though they're not true tropicals they can take it a bit warmer, up to 24 as max. Years ago they were kept as trops though so a lot of people aren't aware of this.

22 is max for White Clouds though.

Ok, thanks for the advice Noodle. I had assumed that anything within the caresheets was fine and have had my temperature set at 22 for a while now. Perhaps an ideal temperature could be made clearer in the caresheets as I didn't realise I had been making my minnows uncomfortable all this time. I've turned the tank down to 20 for now as I don't want to make it too cold for my cherry shrimp.

Any advice on anything else I could add to the tank would be much appreciated.

Hi

When a range is quoted for temp, around the middle is best for any given fish, but the upper and lower limits are OK at a push. The problem with adding trops in with temperate is that ALL of the fish are on one of their limits so it's too much of a compromise.

As to what else to add, you could try some of the other Danio or White cloud variants.

I take it these would school ok with the fish i have currently? I.e. if I added 2 Leopards or Pearls they would be happy in one big danio school with my Zebras rather than having to build up 2 schools of 6 of each to keep them all
happy?

Hi

Yes, that's right. These are mostly in reality the same fish, just selectively bred colour/pattern/fin variations from the original Zebra Danio.

They'll quite happily join together as one group.

Excellent, I've had my eye on the Pearl Danios in my LFS for a while now! I also saw Golden Clouds in there so will consider 1 or 2 of those to brighten up the minnow school.

Thanks again for the advice Noodle, it's very much appreciated.

You're welcome - sounds like a good plan