Is it white and cotton-like? White, cottony growth that appears on healthy tissue can indicate Columnaris. (If it grows on previously injured or infected tissue, it's more likely to be Saprolegnia, a fungus.)
Columnaris is caused by a type of gram negative bacteria called Flavobacterium columnare
. The bacteria is often found in aquariums, but the fish's immune system can usually keep the fish healthy.
Once it takes hold, Columnaris can be aggressive so if this was my fish, I would treat it quickly. Here are several suggestions on how to treat/control Columnaris. Do whichever seems best to you, based on the species of fish and your own preference. Option 1) Treat the sick fish only and use a gram-negative antibiotic.
Quarantine the sick fish in a hospital tank. Since Columnaris can spread quickly, I would treat with a gram-negative antibiotic. Everyone has their own preference for antibiotics. For treating Columnaris, I've found the furan medications (Nitrofurazone and Furazolidone) to be highly effective. Some brands names are: API Furan 2
, Hikari Bifuran
, Jungle Fungus Clear. Option 2) Treat the sick fish only and use only holistic treatment.
Quarantine the sick fish in a hospital tank. I'm not familiar with apistos, but from what I read, they don't tolerate salt. (The bacteria that causes Columnaris doesn't like salt.) Do you know how they are with mild antimicrobials such as Melafix or Pimafix? If they're OK with it, one of these might be an option.
Other suggestions that may help:
- lower the water temperature towards the bottom of the comfort range for the inhabitants. Lower water temps will slow down the bacterial growth rate.
- increase the frequency of water changes. This will physically remove the bacteria from the tank.
Good luck. Keep us updated....