Colour change from black to pale brown? (Pleco)

[Tidebreaker]

Hello!
If any of you know what might be wrong with my Sailfin Pleco please say somthing!
I fear he is sick since a few of my smaller fish died this week.
I have a 50 gallon tank with:
1 (7 inch) pleco
4 (1 inch) Kissing Gouramis and one that is 3 inches
3 (4 inch) Silver Dollars and one smaller one (1.5 inch)
and last but not least my Shubunkin Koi fish (2.5 inches)
I also have three snails.

I am not sure what is wrong with my fish but I'm guessing he is stressed. I'm planning on giving away my 4 Silver Dollar fish to a friend but I don't know if its enough.

I currently do not know the Ph level or ammonia level.
but I do put in ammo lock which helps with too much ammonia.

Since these are tropical-ish fish the lady who i received them from said to keep the water temperature around 78 degrees Fahrenheit.

I'm worried I'm stressing the poor guy out. Can some one tell me if it might be a sickness or stress..?

(I cant take a picture because i'm doing this on the computer and my phone is broken currently D:)

Sorry!

[fat meloe!]

Some catfishes, like the chameleon whiptails, naturally and harmlessly change color, and others display special "stress coloration" when unhealthy. Also, stressed fish that change color are often paler/duller than healthy ones; PlanetCatfish and Amazonas article-writers have noted that an ugly fish at the store can often color up once lovingly cared for.

Maybe search the cat e log and see if the stress coloration of either the sailfins (there are several different fish known as sailfin) or similar-looking plecos resembles your fish. For example, there is a stress-color pic on

Ancistrus cf. cirrhosus

, and it might not be an exact match but it could be helpful.

Unfortunately, my expertise is not in fishes, these are just a few tips. I have experienced nail-biting disasters with fishes too, and I know it is very unnerving.

Cheers, and good luck