We have a 300 gal salt water tank and after a year felt finally ready to add more fish (we have seven chromis that have survived the year). We set up a 75 gal observation tank three weeks ago at which time we put rock that had been in our display tank into a refugium. Two weeks ago we put a few pieces of live rock from the local fish store into the tank. We purchased two benggai cardinals that had been in the local fish store for two weeks as part of a larger group. The whole group appeared healthy. We put the two in the tank last night, they stayed on opposite sides of the tank initially. We placed a 40W bulb in a lamp in the room so they would have dim light. When I peeked at them at 7am and 7:30 they seemed content, six inches from each other in the center of the tank. When my husband entered the room at 8am, one of the cardinals was wedged under a piece of the rock. The other was hiding behind the rock relatively near him. When I moved the rock, the cardinal just lay on the bottom. He had no overt damage, but I did not want to stress him by examining him closer. His color was not as vibrant. A small spot of brownish gelatinous material was near him (size of tip of little finger)(Could have been under rock and not related). He had slow "gasping" respiration. We left them, having to head to work. The tank had 0.25 ammonia last night. Tank ammonia circle monitor looked the same and the temperature has been steady at a little over 80 deg. Wondering what could have gone wrong. Although we have left, wondering if anyone would have intervened and how. Nervous about any future fish as well.

