My fish are sick

Question
I have a 15gal. tank and I've had it for years, it contained 2 large gold fish and a very large sucker fish. I recently bought 2 new goldfish and put them in the tank. Everything was fien for the first week or two and then I started to notice problems with my largest goldfish, he was not swimming as he usually did in the tank and seemed to be sinking to the bottom, I thought it was just to get air, so I wrote it off. Shortly after he started getting red streaks that looked like blood spots on his sides. I took him out and put him in his own tank and with in hours he was dead. Now more recently I have noticed on my other 2 fish, which are black, small white spots. I thought they might be Ick so I bought treatment and treated the tank for the recommended time, one of them has slowly been acting normal again while the other is still very lathargic and sits at the bottom of the tank. They both still have the spots but it seems to be getting worse on one while it's getting better on the other. I tested the pH levels and all is normal. I don't know what could be causing htis change in them and I don't know how to treat it. I am confused because the sucker fish seems to reamin fine through all of this. He doesn't have spots or act funny, they all seem to be eating well. Please help me save my fish before it's too late!
Sincerly,
Kristin

Answer
Hi Kristin,

The problems started when you added 2 new fish to your tank, which was already overstocked. Plecostomus (if that's what you have, "sucker fish" is what people call a Chinese Algae Eater sometimes...this isn't a fish that is recommended as a tankmate for goldfish, do a Google.com search for plecostomus to verify that is what you have) grow very large, I have personally raised some over 12" in length! Goldfish are messy fish, and 2 in a 15 gallon is seriously pushing the limits of what your tank can hold - there's only so much waste that 15 gallons can dilute. A 15 gallon tank simply cannot safely hold 4 goldfish (fancies?) and when you add on the extra waste your plecostomus produces, you see you have a tank that was inevitably going to be in trouble.

To keep all that you had intended, you would need at least a 55 gallon tank. As the water quality plummeted, your goldfish indeed contracted ich. When your fish show signs of ich, it means the whole tank is infested, so your pleco may show signs of ich in time, although the medication may have stopped the infestation already, depending on how rapidly you administered it. Some ich medications are quite harsh, and will hurt the beneficial bacteria which keep your tank stable. As you noticed, medication lowers the level of oxygen in the water, so it's a fine idea to have extra aeration (bubbles, from an air pump, airline tubing and airstone) going when you are medicating...

Is your course of medication finished? That is, have you treated for the recommended number of times and days? If that's the case (different medications have different treatment schedules - check the back of the product for details) then I would put a fresh filter cartridge in your filter, which will remove residual meds. Filter cartridges contain activated carbon - if your filter isn't of the "cartridge" type, you can add activated carbon to your filter in other ways, check your local pet or fish store.

After adding carbon, do a large water change, about 75%. Then the next day, do another. This won't stress the fish nearly as much as it will being in a tank that registers ammonia or nitrites! Incidentally, while pH is helpful to know, it is not very important in the case of keeping plecos or goldfish, since both species are highly adaptable to pH. What you *need* to be testing is ammonia and nitrites, as well as nitrates (with an A). You see, beneficial bacteria convert ammonia (very toxic) into nitrite (toxic) into nitrate (much less harmful). An established, healthy, *cycled* fish tank never registers ammonia or nitrites - these levels are always 0 ppm. Nitrates are 20 ppm or less. If these levels are higher, you ought to perform water changes every day, until they come down. 50% daily for a week would not be too much, in your case, and when things settle down I would still change 50% three times weekly. Always add dechlorinator if your tap water has chlorine (all city water does, and some wells are chlorinated) and try to make the new water a similar temperature.

Does that sound all right? If you follow my advice, your sick fish should recover. Fancy goldfish are not as hardy as common goldfish (which have not been genetically manipulated the way fancies have, to produce those desirable traits like buggy eyes and hunched backs) however, they are still rather hardy. If you keep up with the water changes, you should see a rapid and steady improvement. Get them out of this emergency condition, and then you can start to focus on other aspects of their care, such as their diet...

Did you know goldfish are vegetarian, and thrive on a diet of Spirulina algae, terrestrial and aquatic plants?

Here's a few articles on goldfish feeding:
http://www.kokosgoldfish.com/food.html
http://www.wetwebmedia.com/FWSubWebIndex/gldfshmalnut.htm

Do check out the home page of those sites, especially Koko's since you keep goldfish.

Here's a few more sites:
http://www.goldfishparadise.com
http://www.goldfishconnection.com/

Also check out this site for general aquarium information:
http://freshaquarium.about.com
It's searchable, and all the information is simple and easy to understand. Please do have a read at those sites!

I hope that helps, take care.
Nicole