The cheapest one around, you don't wanna spend $80 on your eels lunch!
Lol just kidding, feed it well and it'll probably be good. I'm no clam expert, I know @skinz78 has like 400 of them
DERASA is the hardiest. It is known. Next hardiest GIGAS, SQUAMOSA ,MAXIMA, least hardy is CROCEA.
Strong illumination. No Angel Fish. I like placing on bottom of tank. If clam is not opening , a fish may be picking at it. This will kill clam pronto. Occasionally , there is a tiny white snail on shell, that can multiply and kill a clam. Check outer shell of new clam, for these. A tiny bit larger than grain of rice.
What eel are you thinking about? Small ones can be a containment problem . Find a way to get in sump. So with Mangrove, will eel be able to Houdini it?
Eels can be trained to take a piece of krill directly from your fingers. This is a good way to impress your friends and confound your enemies!