Stiff right pectoral fin on my SAE

Question
I recently got a ten gallon tank I have 3 sunset coral dwarf platys and 9 red wag fry in a breeding net, I also have a Siamese algae eater, I haven't had any real problems with the tank other than finding the mother of the red wag fry sucked up my pump, but I got a cover for that to keep other fish from swimming in and coming to the same end as her. I do a 50% water change once a week and I have had the tank about a month, My PH level is floats around 6.0 to 7.0 nitrites are at 0ppm, I noticed recently that my Siamese algae eater has been really lethargic and it only moved when I tapped it I scooped it up with my net to get a closer look and he seemed to have this film coming off of him, it was sort of a milky white color, like he was shedding his skin. He also has a very stiff right pectoral fin, it just sticks out and he cant moved it, and when I touched his fin it seemed to be stuck in an outward position and very hard...what should I do, all of my other fish are very healthy and happy, I have five plants in my tank 4 dwarf water lilies and another one that I'm not sure of the type...I don't know if he has some sort of disease???? please help me out I don't want him to die.

Thanks Ashley

Answer
Hi Ashley
Honestly, for the fin problem, I have no idea what that is.  If I had to guess, I would say an injury, but even that's a stretch.  That's really bizarre.  I tried doing a search as well, and didn't come up with anything on that.

The white filmy stuff on him...that can be several things.  First, I want to point out about your ph.  It shouldn't be fluctuating that much.  Even small changes can cause ph shock in fish.  Do you notice it changing dramatically after you do a water change?  Try checking it before changing the water and after the next time you do it.  Rapid ph changes like that going on can cause the skin/scales to look like that.

Another thing, you said the tank's been set up for about a month.  What's your ammonia and nitrate levels reading?  A month isn't really enough time for a tank to cycle completely, but you're doing large water changes every week, which may be affecting that.  Hard to say without knowing those other levels.  Ammonia can cause the fish to produce excess slime coat, though I don't know if it would necessarily have a white appearance to it.

Another possibility is parasites.  Those can cause the fish to produce excess slime in response to the parasites on them.  Have you noticed before or currently was the fish darting around, or rubbing on objects in the tank?

Does it look like it has stringy strands hanging off of it at all?  And how do the tail/fins looks, aside from the one, any fraying or splits, reddness?

Christy