White patch on ember red tetra

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AC Members
Jul 31, 2022
Thanks for your insight jake. Indeed I do think that it was just a scratch. And I was happy that it didn’t spread and she didn’t have a change in behavior. I’m positive the extra water changes that fishorama recommended helped her to heal. Is it possible for them to develop a new fungal or viral or bacterial infection in a tank that they have been in long term and nothing new has been added? No live foods either beyond’s the snails that breed in the tank for the assassin.


AC Members
Jun 28, 2006
SF Bay area, CA
Some things like some bacteria, algae, some fungal spores etc are a part of the natural environment everywhere. They may be fine at low or usual levels but are waiting for a chance to spread if the right conditions are met. Stressed or weakened fish, a swing in water parameters, it could be anything that allows whatever to get a big foothold.

Fish & live food can often carry a low level parasite load that doesn't necessarily cause trouble but can if a new fish or very different parameters allow for their spread. Some "critters" are harmless & may be a form of live fish food. I have a many years old colony of blackworms in 1 tank. My fish may eat some but after all this time I'm sure they're fine. I also see stylaria worms once in a while, no big deal but I don't know if I have now fish that will eat them.

& of course anytime you introduce new animals or plants there's a chance they come with "something". There isn't a realistic way to prevent all chances of introducing "things". But I strongly suggest a quarantine tank for animals & at least a chlorinated tap water soak plants & "used" decor. I never allow "other" tank water into my tanks as best I can.