a peculiar fish disease

Question
Hello Christy,
my name is travis and I have a 90 gallon tank containing pleco's, cichlids, and a few crabs. One of my cichlids a pike cichlid has been developing red scratches on his sides. He will swim around the tank constantly bouncing off the gravel and ornaments as if he is scratching hisself. He is the only fish with these symptoms and i'm confused as to what the cause is or how to treat it to make him more comfortable. He has a good appetiate and always eats. Let me know if u can help me out. Thanks

Answer
Hi Travis
That's a good size tank you've got!  I've got a few questions for you, because there's several things that may be causing him to scratch/flash, which can be fluctuating ph, fluctuating temperatures, parasites, bacteria, or water quality.  So we'll start with the easy stuff:

1.  What are your water parameters?  PH, Temp, ammonia, nitrites, & nitrates?  (the actual numbers for thosenot just "in normal range")
2.  How often do you do water changes?  And how much water do you change out?
3.  How long has the tank been set up?  & What and how many fish are in the tank?
4.  Do any of the fish look like they may have ich?  That would look like the fish was sprinkled with salt on their body/tail/fins (but may be starting out, so may only have a few flecks on them)& check all the fish.  Or do any of them look like they have a gold dust on them?
5.  Do you see any worm type looking things attached to the fish, check especially around the gills and base of the tail/fins?
6.  Do the red scratches look like actual scratches/injuries from flashing/rubbing on the objects in the tank, or do they look more like red streaks?
7.  Do you use tap water to fill the tank, if so, do you use a dechlorinator to remove the chlorine?
8.  Is the fish gasping at the top of the tank for air?
9.  What kind of pike is that, and do you know if it was wild caught or tank bred?

I'm not real familiar at all with this breed of fish, I did find this site about them, seems to have a lot of info on them.  Just passing it on...

http://www.geocities.com/NapaValley/5491/art-pikeintro.html

Get back with me on those answers and we can try to narrow down what his problem is.  Like I said it could be a number of things, and I don't want to tell you to treat for flukes, when it could be a ph issue.  
I'll be looking for your response!

Christy