Pregnant Bala

[n3ont3tra]

I don't see how it could cause swelling, though. What's your water change schedule?

 

[richywiseman]

He died this morning, I change 20% water every week without fail water is perfect. Must have been an illness?

 

[Tokis-Phoenix]

Its posible the fish has constipation- the bala shark may have caught less food to eat in the guppy tank, which is why its swelling went down, but now it is back in the main tank it may be getting more food, make the constipation bad again.
Personally i would put it on a 2 week diet consisting of either chopped up blanched spinach diet or chopped up de-shelled cooked pea's, with frozen or live daphinia added in- the veg and frozen or live daphinia should be able to sort out any digestive problems the shark has as long as you seriously cut down or stop feeding dried or high protein foods while it is on the diet . I would also advise treating the shark with an anti internal bacterial med like "anti internal bacteria" by Interpet just in case the bloating is caused by an internal bacterial infection causing fluids to build up in the fish as well.