Why is my betta fish suddenly a ..

Brief：
I got home today and fed it, it was fine. Then I went out again and when I came back it was suddenly a paleish sick color instead of its usual bright .. 

I got home today and fed it, it was fine. Then I went out again and when I came back it was suddenly a paleish sick color instead of its usual bright blue color. What's wrong with it? The temperature is fine, nothing looks bad.

Probably a build up of toxins in the water. Change some of the water now, don't feed it for a few days, and change some of the water again. Be careful with what yo are feeding, you may be putting in too much food. Your local pet store will test a fresh sample of water for you to confirm it.

A well they are injected with food-coloring anyway, but if everything is fine, i wouldn't worry about it. as long as his fins don't look coated. not sure poor water quality, excessive ammonia burns and or high nitrates present in the water, leads to poor immune system and less coloration. Just like humans who are sick, fish also turn "pale" You can fix this problem by keeping the environment clean, and frequent partial water changes :) This also includes insectiside, cleaners and excessive medications in the water, this may lead to your fish becoming pale.. He mighthave a fungus infection, have you changed the water lately? Did you buy it from petco? The problem with betas is they are not bread properly and they are sold in mass quanitites so they aren't the healthiest. If you really like bettas you might want to get one from a fish only store. Or take him into a fish store and have them take a look at him, don't go to petco or any big chain stores, they don't know anything. For tonight try changing the water and see what happens in the morning. put some no itch in the tank with the fish , after u do a water change clean the tank then put the no itch in it keep the fish away from any other fish till it has cleared up if u caught it early enough u might be able to save him but if not im ss , bettas noramally have a life span of 2 years some longer but the average life span is 2 years adn thats with proper care feeding water quality etc , It seems normal for betta fish to alter their colour a little bit over time because I've had 5. But changing that rapidly to that sickly tinge does sound odd. How long have you had your betta? They normally live for 2 years (sometimes a few more if you're lucky), so it could be that he's dying. Don't feel bad, because it seems like you're doing everything right and it happens. Good luck to you and your fish! It could just be a thing of growing up. Genes change, too. Bettas have been known to change colour yes its rare but it happens.

A person had a pure white betta but a month later it turned red and blue.

Also sometimes fish change colour lightly when the tempature changes. He probably has fungus. there are betta specific fungus medications available.