I just recently got my first two axolotls they are each in their own 10 gallon tank. Recently, one of them has had what appears to be an injured gill, the tank is filtered with a sponge filter, the water conditions are usually good with no detectable ammonia and usually no detectable nitrite, although i am fighting occasional spikes. I am attaching a before and after picture its kinda hard to make out the gill that is damaged. I was wondering if this was an injury of an infection of some sort. I will try and get a better picture of the gill if she cooperates. It looks more like an injure as i do not see anything that looks cottony, but there isn't anything in the tank that I can think of that may have caused the injury. Thanks in advance for your responses.