As stated above. The law doesn't have to specifically address fry. If catching a sport game fish for aquaria, the size restrictions have to be satisfied as to minimum length/weight along with the state allowing the legal-size sport fish to be retained and transported alive. Alot of states also restrict gamefish to types of catching methods (eg: normal tackle, trot lines, traps, dipnetting etc.)
Read the fishing laws available anywhere licenses are sold.