Harlequin Rasbora

[Dan1984]

Hi guys thso is my first post. Basically I'm worried about my harlequin Rasboras, they'd been in quarentine for the last 3 weeks or so, at first they were rubbing in there but that died down after they had been treated with a course of melafix and some praziquantel. Anyhow they were moved into my new 240l tank on Friday night so they would have all night in the dark to settle in, this morning one was gasping at the surface so I kept an eye on him. 15 mins later 4 more were gasping at the surface, I thought it was a lack of oxygen in the water as their last tank had a filter sponge so lots of bubbles. I added an air stone and within an hour all was OK they were all swimming about normally, now I've noticed one purple rasbora swims then sinks right to the bottom then swims off again, he's also keeping himself apart from the group. In the last 10 mins I've noticed that he's gone back to gasping at the surface too.

Update:
The purple rasbora died this morning, and now lots of the others are rubbing against plants and ornaments ?

Any help?

Dan

 

[Aiken Drum]

Do you know the water parameters of your 240l?

Are there other fish in the 240l or just the new fish? If there are other fish how are they?

You say the 240l is new. Is it cycled?

Edit: How did you aclimate the fish to the new tank?

Are there any significant differences in water parameters between QT and display tank?

Are you 100% you used water conditioner in the 240l?

 

[Dan1984]

Sorry yeah I should have included all that, I knew I'd forget something! Ammonia is 0, nitrites 0. 25 nitrates 20 and I am about to do a water change. The tank is fully cycled, seeded from another filter. Used Api stress guard in th 240l, I didn't acclimitse them to the new tank as the parameters were the same in th QT tank. Finally they are the only fish in there although there are 2 assassin snails and some pond snails. I hope that's answered all of it

 

[fishwonder]

Used Api stress guard in th 240l, I didn't acclimitse them to the new tank as the parameters were the same in th QT tank.

Might want to check your water conditioner here for possible issues (Aloe Vera).