Blue Catfish Blue catfish are round in shape with a flat belly, as they age they frequently develop a distinct hump in front of the dorsal fin. Their anal fin is long and has a straight margin and 30-35 rays of equal length. Their color tends to be shades of blue-gray, although they can take on a silvery appearance. The belly typically fades toward white at the very bottom. Their skin is smooth with no scales and generally free of markings.
Most blues are not sexually mature before reaching 24 inches. They spawn in late spring/early summer when water temperatures reach 75°F. Blues are nesters and prefer cavities in drift piles, logs, undercut banks, rocks, or other such areas. When young these cats pursue a varied diet, but as it grows it tends to eat primarily fish. Blue catfish commonly grow upwards of 40 pounds and weights over 100 pounds have been record.