I have a 3 yr old goldfish in a 10 gal tank that's about 3 inches with two other smaller goldies that has been sitting on the bottom of the tank since his water change (a few days ago). He can swim to the surface fine when disturbed and still eats. but spending more than usual time sitting on the bottom and less active like he usually is. i've read that can be flukes or constipation. i checked the water, all levels such as pH, ammonia, nitrite are in good condition after his new water change. so it doesn't appear to be a "swimbladder" problem since he CAN swim, but just doesn't. i noticed he has a slight, very lightly red spot on his belly. i think it's from sitting on the bottom so much and crawling on the bottom because he's been so lazy and inactive. this has actually happened once before where he spent majority of his time at the bottom and i was trying to do all i can to help him. and then he was fine after a week or two and now it's happening again. i never quite figured out what was wrong with him last time when i was trying to help. please help this time before anything bad happens!!! i've had this fish for 3 years and i love him very much!!! Thank you so much!

cathy

Of course it could be that you forgot to dechlorinate. You also did not mention a test for nitrates. This is an important and common problem among Goldfish cases. High Nitrates cause weakness and "poor-doing" in Goldfish, levels over 100 are highly suspect.

So, start with nitrate testing.
A shotgun therapy with little more than 0.3% salt is also commendable.
If the salt fails to make an improvement, after all the water quality is surely established to be "good" then consider a second remedy for Flukes in the form of Fluke tabs, with a water change in between, or perhaps some Praziquantel. There's an article on praziquantel here in this web site. Thanks
Doc Johnson