Machinepriest, thanks for taking a look at my diorama and leaving a note. Long answer I went on vacation.
The algae eater (a plecostomus) jumped out of the aquarium died. Looked (smelled) all over for it, could not find it.
Time went by. . . I found its skeletal remains in a nearby potted planet. Layers of lacquer later, I had a “Dread God.”