Rainbow Shark Swimming Funny

[squidneh]

Tank Size: 75g
Water Readings as of this morning: Ammonia 0, Nitrites 0, Nitrates 5ppm
Diet: Shrimp pellets, tropical flakes, blood worms on occasion
Water Changes: 25% twice a week via vacuuming
 
Symptoms:
-swims tilted to one side for a few seconds at a time, is able to swim normally for the majority of the time, but does seem weaker than usual
-will 'twitch' his head very fast from side to side occasionally
-no outward signs of sickness/distress (no lost scales, no clamped for torn fins, etc)
 
I just recently moved him to this larger tank, but prior to that I had witnessed him behaving a bit oddly, as in darting across the tank erratically for no apparent reason and then tilting to his side a bit, then going on like nothing happened. 
 
I don't want to lose my sharky 

 

[Ch4rlie]

Darting around can be down to bad water quality or parasites perhaps

To be honest may be worth looking up hole in the head disease as well to see if symptoms match that or one to eliminate.
 
Sorry, not much help here hopefully someone can suggest more and help more than I can.

 

[star4]

Have you added any new fish or plants recently? Check sharky's eyes for any grey spots/patches. Can you see if his gills are red and inflamed? The head shaking could be a sign of gill flukes, but that wouldnt account for him swimming on his side, but would account for appearing weaker (less oxygen going in his gills).
 
Did this head shaking come on really suddenly, or has it been gradual? and did it by chance start after a meal of bloodworms? I only ask because I have had greedy fish suck down bloodworm so fast that some has been stuck in their gill plates before. They usually manage to dislodge it though after shaking their heads.