some one help me please.. when i just woke i saw one of my bala sharks trying to swim .. but he wasnt moving at all.. nows it gotten a bit worse.. his moving every slowly and hanging upside down at time.. watching him do this is killing me since i love him so much =[.. his the biggest one out of the 6 bala sharks i have, his about 10ich to 11?. they all are in a 240 gallon tank .. water contions are fine i checked yesterday.. and ive had this tank running for about 9 months now... haven't added any other fish in maybe 5 months.. its a bala shark only tank with a few neon tetras. i don't know what else to tell you just some one help me =[