I have two objections to what Gurglar has said. The first is as Trojannemo said, most of the fish in a subtropical location like the waterways in Florida are a very negative impact on the local environment because they do not belong there. They are fish that some hobbyist has "released into the wild" which means they dumped their fish when they didn't want them any more. Those fish, in many cases, do not have any natural predators in the waters and their mere presence has a very negative impact on the fish that would naturally be present in those waters. The second objection that I have is the implication that only farm bred fish are for sale in your local fish shop. It simply is not true. Many, perhaps not most, of the fish in your LFS are wild caught in places that have poor economic resources and are shipped to parts of the world where people like us have the ability to pay for that trapping and shipping. That does not mean that fish in the LFS are tank bred or farm bred but merely that they are not being caught by the fish keeper directly. Shipping losses can run as high as 30%, so the impact of commercial trapping and shipping is worse than the impact of me walking to the end of the street and catching a few fish. I do not personally live in a place where I can catch tropicals that have been released into the wild so I cannot cut out the middle man like that.
As far as Trojannemo's comment about colorless fishes that we can dip net locally here, further north than he is, there are many very pretty fish available locally if you know how to identify them, such as lots of the group called darters. In my home state, the Department of Natural Resources has taken the position that they will prosecute anyone taking any fish from local waters except by hook and line. Any use of a net will get me in lots of trouble here although the laws here match those in a nearby state where the DNR encourages dip netting and identification of what is being caught at each location as a part of their survey process of what fish are living in each waterway. The difference is in the law's interpretation. Both states outlaw netting any "game fish" but the state that I live in interprets that any fish that has not been named as exempt is automatically a game fish. That adjacent state names the game fish and considers any not named as game fish as being OK to net. Neither state has any law that states which fish are or are not game fish, the difference is in the enforcement group themselves interpreting the laws. Darters are a group of very small and colorful fish that will never be game fish to a person who is fishing with a hook and line but that kind of reasoning seldom comes into the thinking of the DNR officials.
For some reason I was expecting you to be a lot older 
. Which is why I say I shouldn't even go dip netting. I've gotten away with bringing stuff back before, not fish though 
. Either way the temptation is there. Again I shouldn't go looking.... 
