Jack Attack

There was quite a lot of interesting aquarium-related activity last weekend. In retrospect, though, I guess I noticed some general behavioral changes a week or two prior. There seemed to be an unusual amount of gravel rearranging, plants being uprooted, and a general reforming of the floor of the aquarium. What used to be a nicely sloping gravel floor was become rather mountainous and hilly. There were large heaps of gravel in some places and deep valleys in between. At the time I wrote this off as something my little loach was doing in search of food, since they are notorious diggers. Since then I have since seen the light.
So, on Saturday, as part of my weekly water exchange, I was also proceeding to smooth back out the gravel, and re-securing the plants. While I was doing that my full-grown (approx. 8 inches long) Jack Dempsey Cichlid became unusually aggressive. Normally, anytime I am doing general aquarium maintenance he goes off in a corner somewhere nice and timid. This time was completely different. He began charging at my hand seemingly in attempts to scare me away. Not ever having seen any aggression before I didn't think anything of it and kept about my business. After failing to rid the tank of my hand, he finally just came in and bit the heck out of my pinky finger, enough to cause a nice steady bleed. It wasn't particularly painful, but it was extremely startling. Like I said, I'd never seen this behaviour from him before.
Here's a little background on Cichlid behaviour in general that might provide some more insight into my surprise. There are three main 'realms' of fresh water aquarium fish. These groups are mostly incompatible and should not be mixed. This means you should not have fish from one group mixed in a tank with fish from another, or else the less aggressive ones will not last long. These groups are leveled by aggression. The least aggressive group is the 'community fish'. These are you smaller, friendly sorts like molly's, gourami's, barbs, etc. Those communities are the easiest to maintain because you usually don't have to monitor aggression levels. The middle group are the South American Cichlids. This is where the Jack Dempsey lives. He would likely kill off any community fish, but you wouldn't want to mix him in with the third group of fish. In fact, Dempseys are on the lower end of the South American Cichlid aggression scale. They'll usually adapt to whatever aggression the other fish have. The third group are the African cichlids. These are the really rough fish. They tend to be much more vibrant and colorful, but they'll kill off any of the fish in the lower aggression levels. So, you can see, on the aggression scale, Jack Dempseys are relatively low.
So, back to this past weekend. After the bloody event on Saturday, I started wondering why there was such a change in aggression. I thought that maybe he was sick or something and, like a sick dog, he was biting out at outsiders. However, the other, newer, smaller Jack Dempsey in the tank was being left alone. Well, apparently not completely left alone... So, the next day, when I first turned the aquarium light on I notice the pair of them huddle around a group of about FIFTY little baby Jack Dempseys! It all became clear. What I thought was sickly aggression, turned out to be an incredibly protective father fish. And to think, the whole time I thought both of the fish were males...haha.
Cheers,

Update: Sorry about the blurry picture. I took a few of them, and this was the only 'decent' one of the bunch. It was kind of an awkward position to photography and I think I was too close. Ah well, you get the idea.