Bettas are one of the hobby's most stunning fish with their long flowing fins and gorgeous colours, so it's deeply disappointing when those fins start to disintegrate. Sadly, this can be a massive vice for bettas and something that should be monitored closely. With this article, I hope to expand people's knowledge on the subject and show just how easy it is to prevent and treat.
What is finrot?
Finrot is exactly what it says on the tin. It's a disease where the fins rot. There are two main types of finrot: bacterial and fungal. Fungal finrot is generally a slow burner with a white fluffy or black border to the affected fins. The fins will start to deteriorate uniformly. Bacterial finrot is often confused with tail biting since the fin comes away in large chunks very suddenly. 9 times out of 10, unless you've seen your betta biting its tail, it's simply down to bacterial finrot.
Prevention is better than cure
Over the years, I've found that there are a few things that can set off finrot in bettas very easily. One of these is, of course, poor water quality. A simple sponge filter seems to be the best filtration system for bettas thanks to its gentle current and ability to be used as a "betta bed". Bettas love to rest on things close to the surface of the water so they can easily grab some air while they sleep. If the tank you have for your betta isn't big enough for a sponge filter, it's too small.
Another trigger for finrot is related to substrate. Just like the dirt in gravel can harm a cory's barbels, it has the same effect on betta fins. If you're willing to clean the gravel more often than usual, it's possible to use it without a problem but in my opinion, sand is the most effective substrate to prevent finrot.
Lastly, tail biting is the most efficient way to destroy a betta's fins. Of course, chomping on their own fins is destructive in itself but you need to remember that bitten fins are open wounds, vulnerable to infection. Infection sets in from poor water quality or stress or both, then you have finrot AND tail biting on your hands which can easily progress to body rot. Tail biting is generally down to either stress or boredom. Moving the tank into a busy room can help, putting a hand in the tank and talking to your betta for 10 minutes a day will keep them happy too. They're surprisingly needy of human attention. I've also found that bettas loathe living in bowls. Going round in circles has stressed out every betta I've ever had and triggers fin biting and other stress related problems.
How do you cure finrot?
More often than not, curing finrot is as easy as making sure the water is clean. If there isn't a filter in there, put one in there. If the filter isn't cycled, try and seed it as per this link: http://www.kokosgoldfish.invisionzone.com/forum/index.php?/page/index.html/_/aquatic-equipment/seeding-a-filter-r246 If you have gravel, change it to sand. Simple as that. Initially, do a 50% water change every 2 or 3 days and after a week, see if you notice a difference. New growth will have a smooth, transparent border initially. Take a look at the second photo in this topic: http://www.kokosgoldfish.invisionzone.com/forum/index.php?/topic/98858-steves-tail-growth/
If the fins are no better after a week, it's time to get the salt out. Salt is the only treatment you'll ever need when it comes to finrot. OTC meds for finrot can be incredibly harsh on bettas, and your pocket! Salt is much more gentle for everyone. Over the course of a week, do 50% water changes every day, adding 1 teaspoon of tonic salt per 5 litres of water that goes into the tank. By the end of the week, you should have some nice new growth on the fins. If not, keep up with it for another week. Once you see new growth, do your regular water changes without the salt. Clean water will be enough to continue the progress.