Often the first question I get asked by visitors looking at my tanks is: "Why is your water so dirty?"
My answer is almost always the same. The water isn't 'dirty' in the sense that it is unclean or harmful to my fish. It only looks like a cup of unmilked tea because my fish like it that way, and as a fishkeeper that is what matters most.
Nearly all of the betta species I keep come from black water environments such as peat swamps, which is why I am so liberal with the use of tannins in my aquariums. Furthermore, I've always found tea-coloured water aesthetically pleasing, much as tannins seem to be maligned in this hobby.
My goal has always been to mimic as closely as I can, the sort of conditions my fish would naturally inhabit in the wild. When you are dealing with particularly sensitive species of fish, it is important that you take those steps to ensure that they feel as comfortable as possible in their tank.
Betta keepers the world over, espouse the anti-fungal and antibacterial properties of Indian Almond Leaves. IALs are claimed to do everything from harden the scales of fighting bettas, to inhibiting bacterial infections. While the validity of some of these claims remains to be seen, there is one thing I know for certain. IALs produce tannins, and a lot of them.
There are basically two ways of using IALs. The first is where leaves are steeped for several hours to create a concentrated 'tea' or extract. The second is where leaves are added directly to an aquarium and either replaced periodically or left to break down. I personally like to use a combination of both methods. The leaves in the tanks help maintain a stable level of tannins, while the addition of extract to water used for water changes replenishes the tannins that have been removed.
I think to see any of the species from the coccina complex at their best, you have to have tannins. The dark water juxtaposes nicely with the iridescence on these fish, and really makes it pop. Moreover, the acidifying properties of tannins become invaluable when you are dealing with species that have evolved to inhabit bodies of water with very soft and acidic conditions.
Peat moss is often used for the same reasons as IALs. While the environmentally-minded may protest its use in the hobby, I still feel peat moss is beneficial in creating the black water conditions required by many wild betta species. While I no longer use peat moss as a substrate, I have several filter bags worth of it floating in my water aging tub, and stocking peat moss 'balls' in each of my tanks. Based on my experiences, tannins from peat moss seem to give water a darker tint than those produced by IALs, which tend to be more yellow or orange depending on the concentration.
Whether you like them or loathe them, tannins go hand-in-hand with keeping wild bettas. If you really want to see your coccina species put on a show, simply chuck in a few IALs, sit back and watch the magic happen.
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.