Poorly corys: to treat or not to treat...

[Alice B]

Hello
I'm really torn as to what to do about my poorly cories. I've just moved everything into a 240l tank. It hasn't been cycled but I've moved the old filter in with it in addition to the new one, and couple of rocks, in the hope that it is part cycled. I'm going to check parameters daily and do large water changes as needed. I wanted to get them moved quickly because the cories weren't looking well. (My mollies and guppies have been fine). As one of the possible causes was the substrate I have left it and, thanks to amazing advice on here, have put a new soft river sand in the new aquarium.
So, my issue is that the cories (albino cories) have been losing scales and starting to look an orange colour. I hoped that the new improved environment and substrate would help them but upon moving them I've spotted that they may have red blotch disease. At least one of them has a red blotch near its tail, and another has sort of a red streak towards its tail. I feel really sorry for them like I am massively letting them down! I have read that treating with salt isn't good for cories. I've got some melafix, should I be putting that in urgently? I'm worried that then what little bacteria is in the tank will also be killed off so I've no hope with the cycling. Also I don't know if I should be looking at tetracycline rather than melafix... Or should I just wait and see if the improved environment fixes things. I suspect that the bacterial infection needs treating doesn't it? I've also got molly fry in the tank. I don't have the option to quarantine as I'm using the old filter so they'd be in an uncycled tank.
Thank you for reading.

I treated my red blotch on my julii cories with Furanace, an old antibiotic, and they had old filter and 10 gallon, it worked.

 

[itiwhetu]

Ammonia and nitrite are more harmful.

The point is, that people except a nitrate level in an aquarium but they don't except an ammonia or nitrite level.

 

[Alice B]

Fish don't accept an ammonia or nitrite level above zero. Nitrate may be harmful but it's correctible without necessarily killing the fish

 

[dskoogler1]

I think cory cats may be more sensitive to changes to their water parameters than some fish. I would make any changes very gradually. It seems that some pet stores lose a large number of their new cory cat shipments and I think it may be too much stress due to too much change. If you do decide to use medication, I would only use it 1/2 strength because they're a scaleless fish.

 

[Coryking]

Are you sure it's not the yo yo doing that. They are the sort of fish to do so

 

[Byron]

Are you sure it's not the yo yo doing that. They are the sort of fish to do so

Good observation. I don't know how this escaped me earlier, but it is certainly possible.

Corydoras and botine loaches should never be housed together, never. The loaches are more intensely territorial, and aggressive feeders--and "aggressive" here does not mean physical attacks, it means more determined when eating, and almost nothing will be tolerated. Ian Fuller notes that often the cories will almost starve when loaches are present.

 

[Elena82x]

Good observation. I don't know how this escaped me earlier, but it is certainly possible.

Corydoras and botine loaches should never be housed together, never. The loaches are more intensely territorial, and aggressive feeders--and "aggressive" here does not mean physical attacks, it means more determined when eating, and almost nothing will be tolerated. Ian Fuller notes that often the cories will almost starve when loaches are present.

I didn't know this.. The loaches are a recent addition (since the cory issue started) though I'd read that they were okay to join my community tank fortunately since I moved to the larger tank and changed to river sand substrate my cories seem much happier, the redness on two of them is still there but it has got no worse in the last month and they seem happy and eating well etc. I'll watch out for issues with the loaches thank you and pay more attention to whether they are all getting their fair share of food.