This topic is very hard to talk about. On a short note, I have sucessfully kept bettas in small glass bowls just fine. Some people will say that they need about 1 gallon or a 10 gallon tank. The problem with this is when is when. Dont forget that most people who say this over and over again, only have 1 or 2 bettas. They dont know what it is like to house hundreds at a time. While yes, it is always best to give a fish the best/largest tank possible, but the fact is they dont need them and can be kept just fine in bowls given good care. Overall bigger tanks are good but there should be no set standard for bettas. It truely gets to me when people talk about this issue and make it that their must be a standard of 1 gallon. If not your a bad fishkeeper. Come'on give me a break.
The one thing that most people arent aware of who support the "standard" as i refer to it, dont know all of the facts/ issues surrounding betta housing. They simple read that they should be in 10 gallons etc... and they preach to the sky about it. But that brings back the question of when do we draw aline. Maybe 10 gallons is too small, we should have 125 gallon standards. Watch how many of those people stop talking. When they can possible do that. Well thats my point. Betta breeders who own thousands of bettas can possibly have millions of ten gallons around for them. But it is important to understand the issues. I will try to explain about how the other half see it.
Petstores
From the petstores veiw, it doesnt make much economical sense to house every betta you get in a 10 gallon tank or a custom made betta brack system. So thats why they are housed in small containers. Most fishkeepers will tell you that is is sometimes worest to put bettas in the community tanks. As it can cause unneeded stress to the fish and the other fish. When bettas are imported, they are shipped in less than 2 oz of water. I have a picture of what they are shipped in(will post soon). Overall i cant blame petstores for housing bettas in small tanks. And personally dont see how you can.
Fish Activist
They want to see bettas having huge tanks. This is all fine and good, but when you really look at it, it isnt very economical or possible for betta owners who have extreme number of bettas. While it is fine to give your fish the largest tank possible, when you deal with alot of bettas, it is hard to find the resoruces or room to house alot of 10 gallons. Also when do you draw the line, is it 10 gallons/betta or is it 125 gallons per betta. Most people will tell 10 gallons is enough. A 10 gallon should run you only about 8 usd.
In conclusion: What ever you decide to keep your betta in is personally up to you. Their really isnt any difference to me, as long as the care is the same or better.
Betta Barricks
Betta barricks are good for holding bettas in massive numbers, while they are alittle smaller generally, they provide the bettas with constant water changes and good conditions. Betta barricks are always being drained and filled. The bad thing is that it is the same water so generally if one fish is sick the others will. To prevent this most people use a UV sterilizer which kills bacteria and paracites in the water before the water is filtered. Some people love barricks and others hate them. Again it is up to the person.
Multi Betta Tanks
Alot of people choose to do this method. Basically they just get a larger tank and use dividers for males or allow the females to live together. I have found this to be a poor way of keeping bettas as too many illness problems can occur. If you can keep the water clean and clear then you can avoid most problems. The clean water is key.
Betta In A Tank
Keeping a betta in a tank by itself or with smaller fishes tends to be the safest way. It isnt very economical when you are dealing with alot of bettas, but if you have one or two, then this is a very safe and good way to keep bettas.