Parrot fish and Red Oranda Goldfish Dying?

Question
My husband and I received a 50 gallon freshwater tank from my in-laws complete with a parrot fish and a red oranda goldfish just about 45 days ago. Previously, the tank had been at my in-laws, and these 2 fish have been the only ones in the tank and continue to be the only ones in there. Both fish are about the same size, probably about 3 inches in length. I'm not sure what the temp is in the tank. I'm going to the store to get a gauge tomorrow. We've added a couple gallons of water and respective quick treat to make up for the evaporation. We had planned to do the first water change this weekend, but didn't want to shock the sick fish anymore. We bought 2 'sucker fish' (sorry don't know the technical name, starts with a P) about 2 weeks ago. Within 5 days, 1 died and then the second died on the 6th day. The fish store checked my water and said it was fine. On to the second part of the problem. Recently, the goldfish started resting on the gravel very often. I asked the local fish store and they said that he was probably worn out from being chased by the parrot fish. Now, about 2 days ago, the parrot fish started to rest on the gravel often and as of this morning, he's floating with his lips in the gravel - vertically. He's still breathing, but he's just not getting his face out of the gravel. I took a closer look, and there seems to be some white filmy substance forming on him. I've read about the bladder conditions and was wondering if I could try them both on a fast of thawed out peas, as another expert had suggested. Any other suggestions?

Answer
Hi Jenny;

You need to make a water change of 25% right away. Hopefully it will help them feel better until we can figure out what's going on. Make sure the new water is the same temperature as the old water and be sure to use a good water conditioner.

The next step is to return to the fish store, get a thermometer and get another water test done. Have them test the following things;  pH, Ammonia (NH3), Nitrite (NO2-) and Nitrate (NO3-). Ask them to please write down the individual results of each test. "It's fine", or "a little off" isn't enough. We need actual numbers. Once I see what those levels are we can go from there. Once you have a thermometer in there you can also let me know what the temperature is too.

Also include;

What kind of filter does it have?
How often is the filter cleaned?
Does the tank have a heater?
Does it show a temperature setting? If so, what is it?
Besides the whitish film, do you see any white specks, red spots, bloody spots etc.?

The fish don't have a swim bladder problem. They are suffering from a toxin or a disease of some kind. Just don't put in any more medicine until we can figure out what it is. The wrong meds can actually make the situation worse.

Another problem you have is that these fish are not compatible. Goldfish are coldwater (60f to 72f)and parrots are tropical (78f to 82f). Parrots are also cichlids and are too aggressive to be kept with a goldfish. They really need separate tanks if they are going to survive.

Let me know about the info I asked for and we can figure this out together.....

At Your Service;
Chris Robbins