Green spotted puffer fish has a black stomach?

Answer 1

Green spotted puffer fish are a fish with very special care needs, and if they are not met, a black tummy is often the result. They are a brackish to marine fish, so they need marine aquarium mix of some concentration in their water, aquarium salt, sea salt, and table salt will not do the trick. When young a small amount of ocean mix, perhaps about 1/4 the amount that would be used in a salt water tank, is plenty, but most keepers find they do best with more as they age, and once past "baby" size seem to do very well in full marine aquariums. They also need a LOT of space - an adult green spotted puffer needs 30 gallons all to himself. They will need hard foods to wear down their beak, snails, shrimp, etc - and NEVER feeder fish. Not only is it poorly digested, but worsens another very common puffer problem - internal parasites. These puffers often have tapeworms or other parasites, since they are wild caught, and the stress of capture and close spaces during shipping only worsen the problem. If your fish gets skinny again only shortly after eating, or has white stingy poo, you likely have internal parasites. Puffers in general are VERY sensitive to water quality, so test your water for ammonia, nitrites, and nitrates immediately. ANY amount of ammonia or nitrites may kill your puffer in days or less, and nitrates in excess of 40 are far too much. Because they are messy fish which produce lots of nitrate and other wastes, 50% weekly water changes are recommended.