Help with sick rasboras - not eating, thin

[Jharvey]

Hi folks - I have been trying to establish a school of harlequin rasboras in my tank for a couple of months now and keep running into problems.

Tank - 29gallon high (cycled for 1+ years)
fish - 4 panda cory cats (doing great)
- 6 harlequin rasboras
plants - 4 anubius plants
parameters:
ammonia- 0
nitrite - 0
nitrate - ~5
pH - 7.4
food - omega one flakes once every other day

I've been adding rasboras three at a time with at least one week in between (with 0 ammonia and nitrite readings). I have had several deaths during those times despite acclimating and having steadily quality water parameters. The six I currently have have been in my tank for at least a month. I had 8 for quite a while, then lost one, recently lost another, and just today another is looking very thin and kind of bobbing slowly up and down in the water column. The others seem better but they aren't schooling well or eating actively like they used to. At least one seems to occasionally chase the really thin/sick looking one.

Any insights?

Thanks so much.

 

[V227]

The problem might be as simple as poor stock. Try replacing your Rasporas with ones from another fish store and see if the survival rate improves.

 

[libertybelle]

I agree, where are you getting them from and have you tried a different source already? When water parameters are good but new fish aren’t doing well it’s often a source problem. When I bought my harlequins I just bought more than I expected to survive because the only source of fish near me was a persmart with iffy stock. Lost a couple in quarantine and another one or two in the weeks after but it didn’t really phase me because water parameters were fine and I was already expecting to lose a few.

Generally the ones that made it past a few weeks/month do great in the long term.

 

[libertybelle]

Do you quarantine new fish? Could be that each time you add a few new ones you are reintroducing something bad from the source tanks?