honeycomb eel

Question
My eel is only breathing on one side I believe (only one cheek puffs out). Do you know the reason or if this is normal?

Answer
Hi Lynn. It is difficult for me to give you an exact answer but I can give you a few different reasons you may see breathing problems in saltwater fish. First of all make sure your water quality checks out okay. Once you have ruled this out you may want to take a close look and see if it could have possibly injured itself in that area. Eels often dart around and a scrape anywhere on the fish is not uncommon. Parasites would be the next thing I would check for. Gill flukes and Cryptocaryon are not that uncommon. Check to see if he is scratching or if there are any worm like attachments near the affected area or any white pimple like spots on him anywhere. Bacterial gill disease is also another culprit however if it is only one side affected than this is most likely not the cause. If he is still eating and doing fine and you don't notice any of the signs I have given you, then you should let it go and take the wait and see approach. You should never treat a fish for anything unless you are sure it has whatever you are treating it for. You can do more harm than good.