During your fish keeping journey, you hopefully won’t have to experience any of the multitude of maladies that affect tropical fresh water fish. Inevitably, however, you will if you’re in this hobby long enough. Furthermore, many pathogens that affect fish are contagious and can spread within your tank and across tanks. Though there are numerous pharmacological options to treat bacterial, viral, and fungal illnesses, that is a post for another day.
If and when you do experience some nasty contagion, it’s crucial that you confine it to a single tank so that you don’t cross contaminate. Some really nasty pathogens can devastate multiple tanks of fish if you aren’t careful. One way to ensure that you don’t cross contaminate is to not share a contaminated net across tanks. How do you prevent that? One solution is to always use only one net per tank. However, a better and more economical solution is to keep your nets in a medicinal soak when you’re not using them. One of the best medicines for this purpose is methylene blue. Though technically an anti-fungal treatment, methylene blue is also used for general disease control.
I keep all of my nets in a three gallon bucket 2/3 full of water. I mix in 1/5 capful of methylene blue. It’s potent stuff, so not much is needed. Be careful with it though. It will stain anything it comes in contact with – skin, clothes, and even your nets. Yes, those white nets you have will turn blue. It’s okay though. It won’t hurt the net itself. I give my soaked nets a short rinse before I use them. Fish stores often soak their nets in methylene blue.
Oh, and if you have pets that might consider drinking from that bucket (e.g., dog, cat), it’s a good idea to keep a lid on it. I cut a notch out of the lid to accommodate the fish net handles (see above).