Betta Fish: Is this fin rot at the bottom?

No but I can help you to heal torn fins and fin rot and even to increase fin growth. Just follow these steps . But to answer your question it could be the start of fin rot or new growth at this stage it’s hard to tell but usually anything that is in a clear tone is new growth. So follow this and repeat this like once a month or two months and your bettas fins and body will be Amazing I assure you ! Ok so 1) get a pot and add 5-6 cups of water in it boil it. Once started drop in a bunch of almond / catappa leafs boil it for 7 minutes (until water is extremely dark) 2) turn off the heat and take out a few leafs and let them air dry you can use them later when we switch out catappa leafs for new ones but make sure you leave some in the pot you want more than usual we want as much tannins at this point as we can get. 3) add freshwater aquarium salt 0.5 teaspoons per gallon of tank water (let salt fully dissolve) . 4) add API STRESS COAT PLUS it’s amazing stuff your going to want to use it from now on during your water changes as well. 5) add a few drops of prime. 6) bump your tank heat up to 80-81 degrees Fahrenheit.7) during the time your tank is heating up the pot should still be soaking and cooling . 8) mix the water in the pot and dump the entire contents of the pot directly into the tank. 9) let it stay and sit in the tank for 7-10 days no longer than 10 days reason being is the almond leafs only have benefits the first week and after 10 days they start to rot and will cause ammonia spikes and nitrate spikes . So now we want the old ones out and ones you boiled and let air dried to replace the old ones. Stay doing small water changes to weed out salt content every water change add your prime and api stress coat plus. 10) CHANGE YOUR BETTAS FOODS to frozen only such as frozen omega one carnivore , frozen omega one blood worms , frozen freshwater San Francisco Bay frenzy 4 food groups they make your betta happy and so much more healthy and fins and colors come in like crazy because it’s stimulating food and full of nutrients and protein( they loooove these foods) remember you can repeat this once a month or every two months all my bettas are so pretty because of this method and you will start to see big changes in your bettas fins you’ll see hope you use this method. Let me know if you do and how it goes for you I would love you to share a before and after pic once u see how much more stunning your betta becomes

https://preview.redd.it/c5b0xv6acjrg1.jpeg?width=1170&format=pjpg&auto=webp&s=eb21afefc01341628843c4a22fcfb59aab2cfd1d

Month AFTER

https://preview.redd.it/eqh0egkgcjrg1.jpeg?width=3024&format=pjpg&auto=webp&s=648288aed4e3fba5b0a0306d03bba87f8910e731

AFTER THIS METHOD