Let's see...
I had a new harlequin in my 10G hosiptal recovering from a fungal infection he came from the lfs with. I have a UV sterilizer on that tank with a outlet hose that goes right into the tank. I had the uv filter & pump off and the harlequin swam up the hose and got stuck right where the tub meets the filter. I meant to take the filter/pump out but got busy and found him back up the tube, but dead this time.
I have 3 sunset honey gouramis. They are like circus clowns. They swim around in a circle of three and have little "slap fests" with their feelers. It's very funny to watch.
I have a pair of lesbian angels who take turns laying eggs every week. They are strongly bonded to each other.
I had some new platies and a new female swordtail who went into my hospital tank. I have a glass with a plastic back strip that fits snugly aroudn the filter, heater, etc, but I had taken the back piece off to accomodate my UV sterilizer. When I got up the next morning, I noticed that 2 fish were missing from the hospital. I looked all over. Finally, I found the female swordtail dead on the floor under the tank. I couldn't find the missing platy till I looked up and noticed it had died WHILE STUCK TO MY WALL about 1.5 feet off the floor.
I have 3 angel fry in a new 29G tank I just bught. One will only eat freeze dried blood worms, one will only eat flake food, and the other will only eat algae wafers I feed the otos I have in the tank. Frustrating lot, but incredibly cute.
I have 2 sailfin plecs in my 55G tank. They like to lay on top of each other. First time I saw it, I thought one was dead, but not so much.
I used to have a dwarf gourami that ruled my 30G cube as a benevolent dictator. He did not tolerate any aggression between fish. Any two fish that chase each other or whatever got rammed by him till they stopped. As long as the tank was peaceful, he was a happy boy. Sadly, my foray into CO2 injection killed him.
In my 30G cube tank, I have one of the nutrafin ladders that are suction cupped to the side of the tank. There are platies, mollies and otos in the tank. In the course of 3 days after I added it, I think every fish in the tank (that was small enough) had managed to get stuck behind the ladder and needed to be rescued. Finally, I loosened the top two suction cups and no one has been stuck since.