cloudy tank and fish turning red/dying

Question
I am having a problem with my tank clouding up. My fish are turning red and not looking to good.I have 2 pacu,a red eyed tetra,a comet,a koi,2 big fancy tailed goldfish,3 cory cats and a few minnows.I have had all these fish for a while now ((around 4-5 months).They have been sharing the same tank the whole time.I lost a fish from whatever is going on,it was an oscar.It was looking losing his black color then lost his equilibrium then died tonight.The pacu have turned more red and their lips seem swollen. I also have a small gold fish (the only one affected) who is also red. 1 of my 3 cory cats is also affected. It has also turned red.Also the pacu have not been eating the last few days and actually look thin.Aweek ago they were fat and healthy. If you could help me to solve this dilemma I would be extremely grateful to you.

Answer
Hi Crystal,
I would definitely make sure to start doing daily partial water changes in the range of 30-50% every day to help your fish out. All the symptoms you described are key indicators of poor water quality. The aquarium may be very polluted especially since the fish you have produce a heavy bioload.

I'm not sure what tank size they are in. But even if its a big aquarium there is some kind of water quality issue going on that needs immediate attention. It would be very helpful if you could test the water. You can bring a sample of water to your local petstore but be careful of the products or advice they may give you. Don't let them sell you any medications just yet. Theres nothing better you can for your fish than water changes. And until we can figure out what is -really- going on, this is the best and the safest route to take.

When you have cloudy water, that is a bacterial bloom due to a high nutrient level from excess waste feeding the bacteria that is clouding the water. The red coloration on the fish sounds to me like irritated skin and fins from bad water. Remember fish are swimming in their own toilet.

*Always make sure when doing water changes to treat the new water with a water conditioner and make sure the temperature is equal to or just a little bit warmer than your tank's.

See how the fish do when they are getting plenty of water changes. Try to get your water tested, and keep in mind the readings should be as follows -
Ammonia-0
Nitrite-0
Nitrate- 20 or less

Let me know how your fish are doing, I hope they recover!
Best of luck,
Susan~