Originally Posted by cgthebeast
Ok so I never had any experience with this type of fish ,but it looks like it could be fish lice.
Fish lice are approximately 3-5 mm long and can be seen with the naked eye on the external body. They have a flattened body (shell) and have a needle-like structure for a mouth. Said needle-like structure is used to suck out the body fluid of the fish which causes the fish to lose its luster while also causing the fish to be uncomfortable; the fish may scrape the side of the aquarium or the substrate in an effort to ease its discomfort.
The previously mentioned parasites can be killed by using copper sulfate medications. Fish lice can also be eliminated of by keeping the arowana in a concentrated salt solution; oxygen content should be increased in the aquarium during this soaking period. Please note that the aquarium must be sterilized once the arowana has been infected by parasites in order to remove any other parasites that may be in the aquarium.
This is thanks to monster fish keepers.
I hope this helped
Thanks dude.. That was kind of what they told me in the aquarium, they suggested to remove the parasite, then apply some kitchen salt to burn the remains (hook) and then 5 drops of methylene blue and wait.. Thanks for the info