You would need to give more info if you wanted help.
Is the bowl heated, how much water does it hold, anything else with him, is it filtered, do you dechlorinate, how often do you do water changes, any changes in appearance, any spots, frayed fins, what is the temperature of the water, does it fluctuate, tests for ammonia, nitrite and ph, what do you feed, how much and how often.
Im glad hes swimming around again, maybe he was sleeping?