dying fish and strange substance

Question
All I keep in my 20 gallon tank is goldfish. I have 2 comet and 2 fancy. They have grown very very large and I've began feeding them food for pond fish. It comes in large pellets, so when one of my fancies, Laertes, began sort of floating towards the top and being sucked towards the filter (without much fight) I realized he may be sick. He has no signs of velvet or ick, and I thought he could possibly have swim bladder disease, but he mostly just lacks energy and tilts to the side, (also trouble breathing). I put him in a quarantine tank and he remains the same. When I was inspecting the tank I noticed strange pink algae type stuff floating around and getting tangled in plants. My other fish were eating it quickly so I couldn't get that good of a look. But maybe it had something to do with Laertes? I've heard of intestinal problems with fancies. PLEASE HELP! greatly appreciated.

Answer
Dear Kelly,
It does certainly sound like your Fancy goldfish Laertes has developed swim bladder problems. This likely stemmed from when you switched to the pond fish food. It may have been the change of ingredients or the bulk of the food may have created a blockage in Laertes digestive tract, which can affect the swim bladder. You did very good by putting him into a seperate tank so he can rest and not be picked on by other fish or being whipped around by the current. Let him fast (dont feed) for a day or two and then try offering him some thawed and deshelled green peas. Mash them and try to get it to him. He will likely have trouble getting them or he may refuse them entirely. Don't give up, keep trying. You can also offer other fish foods that are -vegetable- based only. Algae wafers would likely qualify. But he will need some help in getting any food. Something like algae wafers will need to be presoaked and you may have to hand feed it to him the best you can. Just give him little bits at a time for several days and make sure to keep his water quality is excellent shape by making daily 50% or larger water changes.  We wouldn't want ammonia to be further complicating his sickness since the quarantine tank may not be cycled.
Keep working with him and trying to offer soft vegetable-based foods and he should recover in several days, though sometimes it does take a bit longer. The vegetable foods are meant for providing fiber and such for clearing any blockages in a fish's digestive tract.

I'm not sure about the weird stuff in your tank. My best guess is it might be leftover food, especially since the other fish were gobbling it up so enthusiastically. It's probably nothing serious and probably not related to Laertes  condition, but just make sure to be careful with feedings and watch to see if it reappears.

Swim bladder disorder is a very common condition with Fancy goldfish. It usually comes from the fish eating too much food at one time or maybe they are getting enough variety.
I really hope Laertes gets better and if you need anymore help, feel free to write again!

Best wishes,
Karen~
for more on swim bladder disorder, visit-
http://www.kokosgoldfish.com/Swim%20Bladder%20Disorder.html