The biggest Channel Catfish ever caught was 4 ft/ 130 cm long and weigh approximately 58lb / 26 kg. There are very few unconfirmed reports of larger catches for this species and we can therefore assume that those figures are pretty close to their actual max size. The biggest Blue Catfish ever caught was 5.5ft /1.7 meter long and weighed 100 lb / 45 kg. There are however numerous reports of even bigger Blue catfish being caught during the 1800s and if you choose to be believe these reports the biggest catfish ever caught of this species weighed 150lb/ 68kg. This makes it harder to decide this species actual max size but we can conclude that it at least can grow to 5.5ft /1.7 meter and perhaps more. The biggest Flathead catfish ever caught was 155 cm / 5ft long and weighed 56 kg / 124 lb: Flathead catfish are not surrounded by reliable but yet unconfirmed reports of larger catfish being caught so it is sound to conclude that those figures are close to their actual max size. Wels catfish can grow much larger then the earlier described catfish and even if most large fish that are being caught today weigh around 200lb / 90kg this is nowhere near the largest Wels catfish ever caught since there exist confirmed reports that this species can grow to be 5 meter / 16.5 ft in length and weighing over 300 kg/ 660 lb. There are however unconfirmed reports from Russia and from Europe during the 1800s that this fish should be able to grow to 6m /20 ft and weigh over 350kg /770 lb. The big difference between the large catfish caught today, the biggest fish caught earlier and the even larger unconfirmed reports makes it hard to know exactly how large these fish really can grow. But a maximum length of at least 5 m/ 16.5 ft is relatively accepted.