My name is ***** ***** I have been a Vet tech for 30+ years and a fish keep over 40 years. I need to ask some questions to best assist you.
Can you tell me what size tank you have?
Is the fish housed alone?
Do you have filtration?
Have you checked water parameters?
What is the ammonia, nitrites, nitrates and ph readings?
What type of test kit did you use?
Do you do a full cleaning, or partial water change?
What medications are you using?
You have not responded to me so I am going to go head and give you some information and some things to do to help. I suspect there is a water quality issue. I do not trust the pet shops as I have seen them test and say all is good and when I have tested with an API master test kit the water quality was off. I would like to see you get an API master test kit and test the water. In the mean time Please do a 50% water change and replace with Bottled spring water or declorinated water. This is important as I want to get as much chemical out of the water as possible. Once the water is replaced, do not add any medications, as they can make the fish more ill if not the right medication and also can seriusly change the water parameters. Please start the filter asap to help clear the tank. I would like to see you get a product called Biospira, which is not a chemical, but a Nitrifying Bacteria to help balance the tank and to cycle it. I would also like to see you add one teaspoon full of aquarium salt per gallon of water. The aquarium salt is antibacterial, antifungal and a general tonic. Each day I would like you to continue to do a 25% water change until the fish starts improving. This protocol should help the fish start feeling better. When you test the water you will want the Ammonia at 0, Nitites 0, Nitrates 20ppm or less and Ph 7.0. any higher than those readings, means the the water parameters are off. This is so important. when replacing the water only add aquarium salt for the amount of water removed and not the whole 30 gallons. Please let me know if you need clarification on the instructions. I know you would like to trust the pet shop, but unfortunately they are not well trained in care. If I have addressed your concerns, please take a moment to Rate my service 5 Stars, so I can be compensated by the site for my time and answers.