doesn't eat

-My betta is in a 18 litre aquarium. (4.75 gallons) with a filter, a heater, an airstone and It's around 26-27 °C . I change the water once a week (conditioned water)- (2 litres or so). Also I have a couple of plants, no other tank mates just really small snails that came out of the plants when...

Housing What size is your tank? 2.5 What temperature is your tank? 79 Does your tank have a filter? No Does your tank have an air stone or other type of aeration? no Is your tank heated? yes What tank mates does your betta fish live with? none Food What type of food do you feed your betta...

So Barney's been inactive lately. We've gotten him a bigger tank and have been good about his water changes & temps. He doesn't look like he has any symptoms of the diseases or parasites that I've seen mentioned (no white spots, no gold dust-like stuff, no cottony film on him)...so i cant...