According to the Mayan calendar, the world as we know it will end on 2012. For four of our five hatchet fish, the world has already ended--only one of the poor little guys remains, the others having all leapt to their deaths through the small opening around the heater power cord. One-by-one I've found their crispy little bodies on the wood floor.
We've had the two aquariums for about six months now, and I'm very happy despite these small tragedies. I do the routine maintenance as suggested, balancing the chemical levels, changing the filters, scrubbing stuff down, replacing 25% of the water biweekly, and in the tropical fish tank we've had no problems outside of a mysterious John Carpenter-ish Fog that inexplicably moves in once in a while and disappears of its own accord. Our goldfish tank has been a bit more troublesome: Leviathan had a fungal disorder requiring a week-long treatment with medicines and water changes; Ophelia has had ick three times and a disgusting parasite problem twice; Einstein has had ick and fungal difficulties. But now they all look healthy and chew gravel and burrow into the plants as usual. I anticipate next year replacing our 30-gallon tropical tank with a 75-gallon tank and moving our tropical fish to larger digs: already the gurami and the blood parrot have doubled in size, and our two pleckos have exploded from barely 2 inches in length to almost 6!
I really enjoy the fish. They relax me as nothing else has since my HO railroad set as a child. The color and movements affix me with an aesthetic arrest like that of an infant confronted by a mobile. Each fish has a personality, too, and a rather complex society has developed in the big tank, with Polly the Parrot fish as peacemaker, Jelly Bean the enforcer, Kodos the Thug, and the others mere civilians trying to go about their business. Are the fish as much fun as sock tug-of-war with a dog? No, but with the dander allergies of the Mrs. I have few options. The fish do at least dance ecstatically when you approach the tank, begging for flakes--so there's some interaction.