A 20 gal would never be able to support enough pods to feed a mandarin. You'd be buying them all the time. I wouldn't try to keep a mandrin in anything less than about a 50 gallon. They only eat things like pods, flat worms, pod eggs and if you are lucky live baby brine. The only way I'd try in a 20 would be with one that was proven to eat baby brine shrimp.
Sorry
Chris
Sorry
Chris
