What's wrong with this fish?

Recently, a farmer reported that his sesame grouper could be put on the market, and the price was good, but at this time, there happened to be a red spot crack on some fish, as if it had been bitten by something, resulting in a lot of losses. I would like to ask all the experts, is this a disease? See the following figure: attachment: you need to log in to download or view the attachment. No account number? Registration-is it serious? Did you find any parasites? Fish lice or something? -with this erythema, the fish catchers were singled out, about 60 yuan each, the quantity is not much, there are no parasites, fish lice and so on. There are no other anomalies in the fish itself-the cultivation technology of Pleurotus ostreatus online HD video-@ 004VR-learn! The fish of the landlord customer should be raised in the sea fish steak, which is more like frostbite. After the water temperature drops in winter every year, marine fish are common, such as golden Pomfret. It can be relieved by mixing Vc into the bait. -the eighth floor is right. It is raised in fish rafts at sea. Although there are not many sick fish, we should pay attention to them. Try it like you said-study-you sent it in the wrong place upstairs-parasites