Using leaves in your aquarium
Dried leaves are great not only for wild bettas, but also for a plethora of other fish species. Especially those that come from blackwater type environments, characterised by soft, tea-coloured water.
Probably the most commonly used leaf in the trade, is 'Indian Almond Leaf,' often abbreviated as IAL. Sold most commonly dried and ironed flat, IAL can be added either directly to the tank, used in tea bags, or steeped to make a concentrated extract.
I personally like to add the leaves directly to my tank to not only provide cover for my wild species, and stain the water a rich brown, but also to encourage the growth of microorganisms that can feed my fry when they first become free-swimming. Some hobbyists choose to remove the leaves once they start to fall apart. However, I allow my leaves to naturally decay in the tank as I regularly feed live blackworms, and those that escape into the substrate feed on the leaf as it breaks down.
Just because IAL is the most commonly used leaf in the trade, doesn't mean it's the only leaf that can be safely used in your betta tanks. In fact, there are quite a few leaves that hobbyists use, some that could be growing right on your doorstep. Below I have compiled a list of leaves that should be fish safe.
Alder leaves and cones
I have not personally tested all of these myself but other hobbyists have used them and given positive reviews. Just be careful when collecting leaves that they have not been exposed to any pesticides or poisons as these could harm your fish.
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.