Why does my Betta fish tank keep getting algae so quickly?

Too much light, whether natural or artificial (green/yellow LEDs can worsen the issue) can sometimes cause an increase in algae growth. Moving the light around a bit to see if it helps, changing to a different type of LED, or just cleaning the tank more regularly/adding in algae eaters may help.

Brown algae overgrowth can be due to high nitrates, too much light or overfeeding. Use a liquid home test kit or submit a water sample for testing. Most pet or fish stores will do this for free of for a small fee. If nitrates are over 40ppm, it can be decreased by performing partial water changes. Use only aged or conditioned water that is temperature matched to prevent stress or shock. You can also use a nitrate absorbing filter insert. The algae will need to be physically scrubbed from plants or rocks and can be scraped from glass. Rinse filter media using tank water NOT tap water. Limit light to 6 hours daily, 8 if you have live plants and do not over feed.

Bettas do best in water temperature between 78 F and 80 F. An algae eater should be okay, but it depends on your individual Betta. Some don't mind bottom dwelling tank mates. Watch for signature of aggression and remove the algae eater if necessary.

It is not uncommon to get external parasites living in aquariums. For example anchor worms are really common and will bury into the fish leaving a white trail hanging out. I would suggest changing 70% water to reduce parasite and eggs, clean your filter and then treat the water with bettafix or bettazing which helps to kill parasites. Be careful you arent overfeedibg as this can encourage parasites.

Thanks for using Petco Pet Education Center, formerly Petcoach! I am so sorry to hear about the passing of Norman. If the Betta tank is currently empty, I would suggest changing the gravel and cleaning it very well before putting another fish in it. Make sure to change the water regularly as this is often the cause of issues with Betta fish. Best of luck!

Check the water chemistry using a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform partial water changes to stabilize chemistry and/or to improve water quality. Rinse the filter media in tank water, not tap water, and replace it. Use only conditioned water that is temperature matched to prevent stress or shock. To limit algae growth, maintain pristine water quality via filtration and regular water changes. If possible, turn up filter flow to keep water moving. If this stresses the fish though, do not do it. Do not overfeed and remove any uneaten food promptly. Limit lighting to 8 hours daily and closely monitor water temperature as well. All these can promote algae overgrowth.

Yes, you can rinse filter media (the sponge) using tank water. This will preserve beneficial bacterial populations in the sponge. The plastic filter parts can be rinsed and scrubbed using tap water. Perform a partial water change, no more than 30% total volume, using conditioned water that is temperature matched. To limit algae overgrowth, do not overfeed, limit lighting to 8-10 hours daily and monitor water temp. If possible, turn up filter flow to get the water moving. Algae thrives in slow moving water. Do this only if your fish are not affected by stronger currents.