FISH DYING RAPIDLY!!

Question
I had a platy in my tank, who I think was sick when I got her. She was at the bottom of the tank acting passive and listless. Later she developed what appeared to be a white thread on her head next to her eye. The next morning, it was a white sore, and her eye was cloudy. I removed her and put her in a bowl (only option) and gave her the recommended dosage of tetracycline gel, which they are supposed to eat. Nevertheless, she died in a couple hours. Now, my platies and some of my mollies in my 48 gallon main tank are "sitting" on the gravel. I noticed that some of the platies seem to have tiny white dots. I know this resembles ich, but it doesn't explain the symptoms or behaviors of the others. I have three questions.1.Can I feed them Tetracycline gel when I know healthy fish will consume it?2. Is it a good idea to net the injured fish into a breeder tank attatched to the main tank every day for the recommended three days to make sure they and none of the other fish get the medication (I will release them after they get medicine)? 3. What do you think is wrong with my fish?

Answer
Hi Mary,
I'm sorry to hear about that.

Its very important to check your water quality whenever your fish seem sick. Its vital to know your ammonia, nitrite, and nitrate. Its not hard, and you can use test kits from your petstore or bring a sample of water to your petstore to have them test it for free. As a rule, ammonia and nitrite should read ZERO and nitrates should be 20 or less.

The biggest cause of disease in fish is poor water quality. Even if the water is clean it can be very unlivable with dissolved pollutants. I would definitely as a precaution change 30% of the water everyday for a while until you can further decide where the problem may be. Make sure you always use water conditioner when doing water changes and make sure the temperatures are equal in to your tank or just a little warmer.

If it looks like your fish have ick. It should look something like this-
http://www.fishybusiness-sc.com/images/ickfish.jpg

If the spots look finer in size then it may be velvet which looks like a fine powder in gold or whitish. Both parasitic infections can be treated with QUICK Cure. Or some of the other medications available will work.

Changing the water everyday is very important with any disease treatment. When redosing, just add the recommended dose back into the tank when you change the water. Which should be about 50% at a time. Water changes also help remove excess parasites.

The tetracycline won't do much as far as helping get rid of the spots.

Best of luck and I hope all goes well!!
Karen~