Eye problem
About 10 days ago Diego started acting kind of shy and was not as active as normal. He would come to eat but not play and stayed in the dark most of the time. From his den peeking out I noticed he was not opening his right eye. A day or two later I notice the eye was staying flat while the left would be raised. He would open it just a little when he came to eat and I saw a white spot on the lens. The spot could have been/be some kind of parasite but with the eye stalk staying flat (possibly swollen) I decided to treat with Tetracycline. I have used it successfully on two infections in otherwise healthy octopuses, once with an eye infection and once with a swollen arm section. Without any real guidelines, I give it for 10 days with the thought that the animal infected is not the target and 10 days has been recommended to kill bacteria in humans. In the last two successful uses, evidence of recovery came at about day 5. With Diego I saw an improvement at day 3 and at day 6 his eye and behavior appear normal but I can still see a fading white spot on the eye. Unfortunately, I could not get a photo of the symptoms but you can see in yesterday's photo that both eye stalks are raised (the left may be just slightly fatter but I could not get a left side picture to compare and to the naked eye they look the same) and I think he will fully recover.
I don't think it had anything to do with the eye problem but also this week the flower anemone that was in the tank before Diego mysteriously released from the rock and was sitting on the sand. I never saw Diego touch the flower but it was directly over (without blocking) his den. I have seen two senescent O.hummelincki pull very insistently on mushrooms that blocked free access to passage and I am guessing Diego pulled up the flower. I was uncomfortable with the flower in the tank (low sting but I have seen reaction and don't mix them intentionally) so the flower was reacclimated to the nano temps and seems to have settled in.