Harlequin rasbora with one red gill
I have 10 Harlequin Rasboras in a 60 liter tank (water temperature is 23 įC, pH around 6.5-7, there is an adequate filter, and the tank is somewhat planted): 5 of the HR:s came almost 4 weeks ago, the other 5 one week ago. Yesterday I also added 5 Cherry Shrimps + their water (bought from another hobbyist).
The rasboras have been quite aggressive the whole time, chasing and nipping each other. Today I noticed one of them has a red gill - could it be irritated/infected or possibly an injury from nipping? Or could it be some illness/parasites? The fish looks fine otherwise, has bright colours and is as aggressive as usually. Actually it looks like itís trying to show off to another aggressive fish. Iíve seen some of the fish getting really pale earlier, presumably because of the harassing, but the injured one is really dark.
Shrimps seem to be fine, and both nitrites and nitrates are down in the tank. I started wondering, did I accidentally bring in some parasites from the shrimp sellerís aquarium. I know I should have quarantined, but I donít have another tank.
Another issue is the cycling. While the tank is fully cycled now, it wasnít when I brought the first HR:s in. I trusted Prodibio Bio Digest (bacteria product) to cycle the tank immediately, which it didnít do, so I had to keep adding bacteria and changing water every day for two weeks before nitrites went to zero. During that time the 5 HR:s must have been stressed. That could have made them weak and susceptible to diseases.
Does anyone have some advice for me? I would be very grateful for help!