Help

I did everything I could. But my guy seems to get worse. He first developed fin rot, I treated him with aquarium salt first-it didn’t help. I was offered by store clerks to use methalyne blue, which I did. 1 small teaspoon/day for 3 days. But no results-he seems to get worse, he doesn’t swim, he doesn’t eat. If anyone has been in a situation like this and knows what I can do please i’ll be delighted if you help!

Fish tank 10gal Decorations fake Ammonia 0 Nitrite 0 Nitrate 10-20ppm Ph 7 Other fish in tank 3 neon tetras

I did everything I could. But my guy seems to get worse. He first developed fin rot, I treated him with aquarium salt first-it didn’t help. I was offered by store clerks to use methalyne blue, which I did. 1 small teaspoon/day for 3 days. But no results-he seems to get worse, he doesn’t swim, he doesn’t eat. If anyone has been in a situation like this and knows what I can do please i’ll be delighted if you help!

Fish tank 10gal Decorations fake Ammonia 0 Nitrite 0 Nitrate 10-20ppm Ph 7 Other fish in tank 3 neon tetras