Help, I checked on my dwarf puffer this morning. He is in a 10g with 9 baby mollies. 7.5 ph, 80 degree water with 2tsp of salt. He was doing fine yesterday, today his anus is hanging out. What does this mean, and what should I do? He is acting like he may not make it, not swimming well and hitting the bottom a lot. He is not aggressive towards the other fish and has been eating well.