My Common Pleco

Question

Pleco   I am a beginner who has made a HUGE mistake with my poor Pleco. First of all, I call myself a beginner because its been nearly 20 yrs since I've had an aquarium and it's like starting all over again. Three days ago I obtained a 20 gallon high tank (24"x 12"x 16"# with one Red Cap Oranda, three Fantail Goldfish #or they may be Ryukin Goldfish...not sure#, and the Pleco. All were very healthy and doing great. It came with a heater and filter which work very well too. Its been my understanding that  goldfish and tropicals don't usually do well in the same environment but these guys were doing fantastic until I got them home. Not thinking about the Pleco, I completely changed out the water and gravel. I did add Stress Coat+ and Stress Zyme+ but of course I completely threw off the whole ecosystem balance #bacteria, algae, pH level, ammonia, nitrites,nitrates, etc... basically EVERYTHING# for the Pleco. The Goldfish are doing great but unfortunately my Pleco looks like something is wrong. He looks splotchy, like his colors are faded in patches all over him. He's still active #moving around at night and hiding during the day# and eating #one algae wafer per day# but he doesn't look healthy now.
The temperature stays at about 76 degrees, there's a hood with two incandescent bulbs #I have them on during the day and off at night# and I've added a bubble stone. Also I had the tank water tested last night at a local chain petstore.
The levels are as follows:
Ammonia - .5
Nitrite - .5
Nitrate - 0
pH - 8.4
Hardness - 150
Alkaline - 300
Chlorine - 0
The employee there encouraged me to do a 50% water change using spring water but I'm not sure because he kept talking about other options too; which really confused me.... please help. I don't want to lose this guy. He was so beautiful and it makes me sick to think that I may kill him because of my carelessness. Thank you, in advance, for any help you can provide :)

Answer
Kelly,
You are correct about not having cold water fish in the same tank as tropical fish. The goldfish need their water temperature to be around 65 degrees at all times. 76 degrees is way too high for them. They might be doing good at the moment but having the temperature that high will lead to a very early death. Another problem I see is the tank is way too small for the fish you have in it. One goldfish needs 20 gallons all for himself. For each additional goldfish you need to have a minimum of 10 gallons. So, to house the four you have the absolute smallest tank they can be in is 50 gallons. Your pleco, can grow to be 2 feet long. His absolute smallest size tank for him is a 65 gallon where 100 gallons would be best. Another reason goldfish and plecos should not be housed together is that your pleco will attach itself to the fish and suck the slime coat off and normally killing the fish. With all fish, especially goldfish, you will want to invest in a water testing kit. Do not use the test strips because they are not reliable. API testing kits are the best. They test for a few things, but the most important are ammonia, nitrites, and nitrates. Ammonia and nitrites have to be at zero at all times. Your readings are not too bad, but we have to get them to not register at all. Nitrates can be as much as 25ppm and still be ok. Normally, the best, fastest and safest way to bring them down is to do daily water changes until both are back at zero. Since you did a complete water change, cleaning the gravel completely I would hold foo on that. The first thing I would do is remove the pleco and put him in your hospital tank. If you do not have one, any container will do. Remove the heater from the main tank and put it in the container with him. DO NOT add a filter. Set the heater to 80 degrees. The reason I am having you do this is because your tank is now going to go through the cycle process. Normally, when we cycle a tank, we do not have fish in it. The ammonia and nitrites are going to sky rocket during this process and it will kill the pleco. Gold fish are a bit hardier but you still have a lot of work to do. Tank cycling takes about 6 weeks to complete. You will want to do 25% water changes in the container the pleco is in because there is no filter with him. You will test your water in the main tank daily in about a week. Depending on the ammonia and nitrite levels you will also do daily water changes. Once you have the pleco in his own tank, let me know how he looks on tuesday.