You're right. A fish won't just become something that isn't a fish. That's because evolution takes time. But a fish isn't just a fish. There are many kinds of fish, and each variety is different from the others. Each individual is different from the others of its kind. Speaking of fish, let me tell you a story. It's a bit long, but try to bear with me. If you choose to respond, please say something that indicates you read it. Once, my family went camping, and not too far from our campsite was a small pond stocked with trout. I decided to do some fishing. Catch and release, as we had brought plenty of food. I tried for hours with no success. Clever things were attacking my bait while expertly avoiding the hook. When I finally got one on the hook, it proved to be a tough battle. It took all of my strength to reel it in. Even once I got it on land, it fought against me. I tried to grab it so I could remove the hook, but it fought me relentlessly. It flopped around so much that the hook, still stuck in its mouth, broke away from the line. The fish fell to the ground. I couldn't believe what I saw next. The fish, lying on the ground, flopped onto its belly and, I kid you not, slithered across the damp ground back into the pound. It only had to go a few feet, but it moved like a snake. The second trout I caught was smaller and easier to handle. I managed to remove the hook from its mouth, and went to release it. Before I could return it to the water, it flopped out of my hand, and landed in the dirt mere inches from the water. It flopped about helplessly until I nudged it into the water. The two fish performed differently on the land. This was because of differences in their genes. Genes are what made the first fish able to propel itself somewhat effectively across the land. What do you think would happen if there were a drought or a landslide that split the pond into several separate pools? Or what if some other scenario emerged that made spending small amounts of time on land beneficial? Would the first fish not be more likely to survive and reproduce? Would the next few generations of fish not be more likely to have the genes of the first fish, and be able to move across short strips of land? After many more generations of the fish who could survive longer on land being more likely to survive and reproduce, would that trout population not likely have gained the ability to spend large amounts of time on land, moving like serpents across the dirt? Over thousands or even millions of generations of these traits being favored, would it not be likely that the trout would be able to live on land for periods of time just as easily as in the water? Could we not consider these to be amphibians? Evolution occurs gradually. Things change in response to the changes that occur around them.