Look at the number of their beards, the shape of their tails and dorsal fins, and whether there are small fins behind their dorsal fins.

These can be preliminarily determined whether they are the same fish or closely classified.

Octopus can be seen from its beard. Octopus has a long beard and a high hardness, so it is difficult to chop a knife.

Catfish has four whiskers and a slightly round and short head.