Dwarf neon rainbows

[Fiori]

I had a group of 8 dwarf neon rainbows ( only got them 2 weeks ago), 2 have died this week and I have moved a third one into a hospital tank this morning. My water is fine - ammonia 0, pH 7.2, nitrite 0 nitrate 20. The other fish all seem fine and I can't see any external signs of disease. The 2 dead ones were found dead in the mornings, just like that and with no advance warnings of problems. I did a water change yesterday anyway, after I fished the last one out.

But...... they are all female and I wondered if they are being harassed to death by the very active males. I watched one before I moved her to the other tank this morning and the poor thing was being hounded! I'm not having much luck with my fish at the moment - it's so frustrating

 

[glolite]

It could be that you just got a bad bunch, I lost a whole lot of giant dannios while the other fish in the tank stayed fine. What ratio male to females have you got?

 

[Fiori]

It was originally 4 of each, as they did'nt have enough in to to make a larger number of females to males. I have one female left in the main tank (with 4 males - yikes) and one in QT - don't know whether to try and get some more at the moment to spread the males attention or not. The lone female in the main tank seems ok for now, but how long will that last!!

I can't see any symptoms of disease to treat, but I don't want to get more females, if there is something going on in the tank.