When I did work for fisheries we used the same nets you would use for goldfish in a pond. Some of the nets had a d-profile to use at the bottom of sandy substrate or cement pen, or a round profile for other applications, mostly with an approximately 1' square opening and extendable handles. Really depends on the fish you are targeting.
That said in many areas collecting wild animals is illegal without appropriate permits. Where I live you are not legally allowed to keep, transport, or collect any wild animal and depending on the animal could lead to significant fines.