So the lab I intern for has a zebra eel in one of its reef tanks that I am in charge of. It is an older eel between 10-15 years and it has not visibly eaten in 2 weeks. It generally eats mole crabs. I tried some jumbo shrimp, which it got excited about and shredded and protected it, but did not seem to eat. What other foods might it be interested in? Is there anything that may be causing this disinterest in food besides age? I have checked the pH 8-8.5 and it does not seem to have any other behavioral changes besides the lack of interest in food.