I'm sure most of you know I work at a pet store. Anyway, we have some Spotted Puffers in there, however after awhile they begin to look shriveled up, and brown under the belly. They are in 150 Gallon systems, so it's hard to keep the whole thing brackish, (there are 24 tanks in the system.) They also look like their spines have been broken, but they swim around crippled for a while, (months) before they die. Ideas?