scubapro. You have in a 40 gallon tank a 20 in. zebra eel, a bluespotted stingray, and a miniatus grouper? Those fish get way to big for a 40 gallon. And a stingray should never be put in a 40 gallon, the need big tanks.
Thereefman- My snowflake eel is excellent, eats a lot (krill, squid, mysis, brine, and a lot of other meaty foods). You can also add a zebra moray eel in your 90 gallon. That would be an excellent addition. I think better than a snowflake. Zebras have better looks, they can live up to 20 years, and are extremely hardy. Zebras eat the same thing as snowflakes to. The only bad thing about zebras are there high price, they are around 80 bucks.