The more and more I think about it, the more I dislike the idea of small aquariums. The difficulty of keeping them aside, I think that there just isn't enough room for them to be happy. If a type of fish lives in the hundreds in the wild, is a group of 6 really good enough? I have my betta in a 5 gallon tank, but even then I think it would be a little cramped with no room to really explore. I wouldn't keep a betta in anything less.
I was thinking about getting a 20-33 gallon tank, but I doubt I will now as I don't think its fair to the fish. I will likely wait until I have the money and room for at least a 55 gallon. Even then I will stick to smaller fish so that the tank seems bigger and I can have bigger shoals for those that require them.
Just my thoughts as of late. Since you have been doing this longer than I have, I'd be interested in hearing what you all have to say.
I agree with you about tank size, but I'm not trying to get all philosophical or anything, but it I believe it all comes down to an analogy, a fish who has never been in the wild but who was born in a tank would it know that there was a wild? Much like a person who lives his entire life without seeing the moon to that person the moon would not exist since he has not experienced the entity we know as the moon. Of course small aquariums should not be used if a fish just cannot live in the environment such as having a Pleco in a 5 gallon, or overstocking an aquarium so that the quality of life for the fish declines. But then some species of fish can actually live longer lives in aquaria. In well kept, appropriately stocked aquariums, fish not only survive, they thrive. I don't mean to play the Devil's advocate here I am just saying that aquariums need not be seen as torture chambers for fish. Indeed certain aquarium/fish pairings can be horrible for fish, but I believe that by researching a particular species and setting up a proper environment for the fish and maintaining the environment to meet the needs of the fish the aquarium can be a good environment for the fish to live in. With today's environmental destruction and extinction of species in the wild, especially in the areas where tropical fish originate, aquarium hobbyists find themselves protecting species that find their natural environment becoming uninhabitable. The Goodeids for example are in dire straits, but aquarium hobbyists are taking up the fight to keep the various species alive for future generations, and maybe release some back into their natural habitat someday. So to answer your question I do not feel that aquariums are intrinsically bad for fish. Of course the wild will always be better for fish. Also, added to the debate is how we have changed fish from their wild forms into aquarium-friendly ornamental fish. I see this change much like what humans have done to dogs and cats. Of course you would not feel compelled to release your dog or cat out into the wild, much is it the same with many species of fish in the hobby today. It may not be our place to genetically alter fish for our own ornamental purposes, but if we produce fish that cannot live in the wild then it is our duty to provide an appropriate environment for them to live in. I feel that aquariums fit the bill quite nicely if well thought out and maintained. These are just my two cents on the issue.