dead fish but live invertebrates

Question
Hi, I have been running a 15 Gals Saltwater Aquarium for over 15 months. Suddenly, last week started dying, but just the fish. The 2 that lasted more were the gobies. All invertebrates are like nothing happened. I had a cucumber, and yesterday I took it out, thinking it may have been the problem. The quality of the water seems fine (Amo 0, Nitrite 25, PH 8). I have a Skilter 250 and I am cooling the water with an aluminum device. I noted that the clownfish, before dying, had clouded eyes and had the skin like a lizzard when changing it. Please, I want to start putting fish, but I don't want them to be hurt again.

Answer
sounds like some form of infection to me, and the nitrIte is very high it should be zero, nitrAtes are tollerable at that level.

i would leave it for a good few weeks before putting any more fish in, do water changes every week and keep testing the water.