Metronidazole, Hole In The Head Treatment..

[Jackiee]

One of my cichlids in my 90 gallon came down with hex/HITH and Popeye.. I've been treating the tank with metronidazole. "API General Cure". The instructions say to dose the tank, wait 48 hours, dose tank again, and then 48 hours later do a water change.. Do you have to do the water change right away at 48 hours? Especially if the fish is still sick? It has improved, but there's still a couple spots on his head not healed and his Popeye is still there.. This Saturday, tomorrow would be 48 hours after the second dose which would be water change time. Would it be fine to wait until Sunday or Monday to do the water change? Or does keeping the medication in the tank somehow cause something bad? I wouldn't think so, but I'm not sure..

 

[Jackiee]

Anyone?..

 

[DrRob]

Generally the intention is to remove something that isn't ideally good for the general tank contents. Antibiotics are remarkably indiscriminate within the realms of their mechanism of action. In general terms they're not brilliantly good for the overall ecosystem in the tank so they're worth removing. However leaving them a bit longer would probably be better than having to redose, but you should, in theory, find that the tank is slightly less stable for a while while the bacterial colonies in every nook and cranny sort themselves out.
 
So overall, a balance. If there are still symptoms then it's probably worth hanging fire, but there is a reason to get the levels back down.