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.
The purple rasbora died this morning, and now lots of the others are rubbing against plants and ornaments 😞