As discussed in class, B.F. Skinner while working at the University of Minnesota discovered a concept called shaping. Shaping is a form of operant conditioning in which one reinforces behaviors that aren't target behavior but that are progressively closer versions of it. This is a common practice for animal training in dogs, horses, and even birds. These animals learn even more complex tricks through the process of chaining, in which the trainer links a number of interrelated behaviors to form a longer series. Each behavior becomes a cue for the next behavior in the chain.
Now, one would consider these methods and think them very possible for training dogs, horses, and other animals. But a fish? Yes, it is possible to train a fish, as demonstrated in this video...
As for the first trick, of training a goldfish to swim up a "chimney," one would start this shaping process by rewarding the fish for going anywhere near the chimney, then only rewarding when it goes near the bottom, and then once again only if it starts going inside until finally you have your fish trained to go through the chimney for its prize. This makes one wonder at the possibilities. While man has trained dogs to do anything from leading the blind to sniffing out specific odors like bombs and corpses, there are many more possibilities that animals could be trained to help mankind further.