You would have to supplement food if the wels are anything like a flathead when it comes to appetite.A friend of mine has a half acre pond that was heavily stocked with bass bluegill,and crappie.He added a 45 pound flathead and within 2 years later their was an extreme reduction of the number of fish in his pond. Now having had the flathead in his pond for 6 years their are hardly any bass left.Plus the bluegill and crappie have been reduced in numbers and size. They very seldom catch one over 4 inches. One more thing in the past 3 years the flathead has been losing weight.They catch it about twice a year and it now ways 39lbs.This is down from 47 lbs the second year it was in the pond.