Bad water condition will cause increase in internal parasite, while this internal parasites inside the fish's body, it will consume the nutrition from the bass and hole in the head is caused by the lack of these nutritions, thats only personal experience and thoughts...
please i dont want them to die its getting worse and i need to know how to treat now my little one has it there 14 and 11 inches how can i treat its got a little better on the bigger one i just been using salt.
dont use salt. start by doing a 50 percent water change. next week clean your filters ... then do 20 percent water changes every other day till your water quality is top knotch... get a water tester kit. and stop feeding them gold fish