Here's one my friend wrote
Here's what we want to fulfill when housing a betta:
- An enriching environment
- Substantial room for a territory to be formed
- Mental enrichment
- A calm environment free from environmental stress (fluctuating temperature, poor water quality, lack of space, etc)
- The ability to explore as done so in their natural environments
When we put this in the context of housing a betta in a 1gallon bowl, this is what we get:
- An enriching environment: We have limited space for planting, meaning it is difficult to provide an environment where the betta can explore the bottom.
- Substantial room for a territory to be formed: We have two scenarios for which fish will establish themselves. The first is called a 'home base' which is often established in animals without territorial nature. For bettas and other territorial fish, we have a territory. Territories are often smaller for singular species, however we cannot establish an adequate territory with a spherical object where there is a complete 360 view.
- Mental enrichment: This can somewhat be supplied in a small bowl environment, however mental enrichment involves the ability to be able to search the substrate (often the smallest part in a bowl), the space for exploring (not adequate in a bowl) etc. A tank provides a much better environment for mental enrichment, so why advocate something that cannot?
- A calm environment free from environmental stress (fluctuating temperature, poor water quality, lack of space, etc): Again, size is an issue here. Secondly, as I mentioned above, we have the issue of the shape of the bowl, which is much more sensitive to vibrations which stress the fish, and we have a complete 360 view which is also quite stressful- usually we try to have one side of the tank towards a wall, which is a 'safety barrier' for the fish. It's not nice to have to keep your environment protected when you've got such an open view, even with plants. Heating is a big issue. Where do you put a heater on something that is shaped like a bowl? Some may have flat sides, but the size of the environment is far too small to safely heat, and is susceptible to large temperature fluctuations.
- The ability to explore as done so in their natural environments: This has been explained in the above paragraphs.
Vs a tank that is of a good size (5 gallons and above)
- An enriching environment: The size of the tank makes it much easier to plant, since we have more room to add substrate, plants, and decor. This is much better for a fish.
- Substantial room for a territory to be formed: again, much more surface area, and we are able to make sure there is no issue of a 360 view being formed with covering the back of a tank, or heavily planting one particular side.
- Mental enrichment: More room leads to more exciting things that can be added. I agree that planted bowls can look and be magnificent, but for bettas? We are much more limited for what we can do for them.
- A calm environment free from environmental stress (fluctuating temperature, poor water quality, lack of space, etc): Although tank size is always a factor, most tanks can be safely heated, we have a good surface area for planting, etc.
- The ability to explore as done so in their natural environments: Again, tank size and water volume are factors of this.
That being said, bowls are often quite small and this is why we cannot provide a lot of these things. Vases that are square or rectangular may be a lot better, but are often tall rather than wide, and I haven't seen a fish that prefers to swim vertically more so than horizontally. Even biorb tanks are stressful to fish, despite them being as large as 60+ gallons. They're just not a good shape.