Meet one of the newest members of my household (peeking from the inside of his secure PVC sewer pipe hiding place):

It's a young Jack Dempsey cichlid. I have a pair of them (each has his own piece of PVC, of course), in a tank with my Flowerhorn Trimac cichlid, which became too aggressive to be kept with my turtle, much less any normal fish. It seemed wasteful to devote an entire aquarium to a single fish though, so I thought very carefully about how to achieve a more or less peaceful balance of power, applying various game theory scenarios in my mind before deciding on the pair of Dempseys. I knew I was taking a chance as cichlids are all very aggressive fish, but in my experience, the Jack Dempsey is not quite as aggressive as the Red Devil/Trimac/Flowerhorn type monsters. The latter often can't be kept even with their own kind, and I started with two and had to get rid of one back in March. The remaining one was the wimp of the two, but now he's gotten aggressive, and I'd never try another pair of them together. The Jack Dempseys are quite larger, though, one of them is twice as large, and the smaller one about the same size as the Trimac. My reasoning was that trouble might start, but would not last, because of constantly shifting alliances. Two Jack Dempseys alone might have fought more, but together, they seem to unite against the Trimac, although the Trimac is so fierce that he's a match for either one of them. If the Trimac gets out of hand, the two will go after him and defend themselves, but they're not quite aggressive enough to attack in a completely unprovoked manner. The Dempseys occasionally attack each other, but it doesn't last, and the Trimac's attacks do not last. It's an inherently unstable arrangement, with no real alliances, but no bitter rivalries. I'm very lucky, because that's exactly what I hoped would happen. It's been almost two weeks now. A peaceful situation it is not, but I think things are close enough to achieving parity of the sort Henry Kissinger might approve.

Also, the fish have probably bonded by having had to make it together through the dreaded Nitrogen Cycle, which is very hard on fish. I have been testing the water for nitrites daily, and changing water sometimes twice a day just to keep the levels down. I stumbled onto a product called Seachem Stability, and I can confirm that it truly is the miracle substance it is said to be, because it has sped up the process from the normal month or so to just over a week. The way it works is by releasing a proprietary brand of spores into the water which cause nitrite-eating bacteria to grow much more quickly than they normally would. It used to be believed that Nitrobacter was the microbe that did the converting, but recent research has revealed that it's most likely Nitrospira. Finally, this morning (after over a week of daily testing and countless water changes), for the first time there were no longer any nitrites in the water -- not even trace amounts.

I'm sure reading about the Nitrogen Cycle is putting regular readers to sleep. Maybe I should try to tie it to Global Warming?