When good fish go bad - Horn dog Midas

My Midas went from a very friendly Oscar like personality fish to a horny, mean little monster. It happen almost in a day. I had added some new decor to the tank and he immediately claimed it as his and started digging and cleaning and doing lots of displays of aggression. Also his fish "junk" is out. When I did a gravel vac yesterday he actually started attacking the end of the tube; charged at it and biting. He has never done this before! He would always go hide under a large plastic driftwood log. He also stated to eye ball my hand in the tank. So I waved my hand toward him thinking he would cower and hide - nope, we started to take that as a challenge and started flaring at me. Wow my little boy is all grown up...

So far the rest of the occupants are alright. He has not decided to kill off his silver dollar tank mates. Though he has taken an intense dislike of the pleco whom he has grown up with. I might just have to get rid of the rest of the fish and get him a woman! Might help him get rid of some of that aggression

Well with our current temp fluctuations it might be possible that the idea of breeding may have been triggerd. When the temp starts to rise in the summer the temp in my tanks always goes up a few degrees. I just posted a video on my firemouths being aggressive to a nic. This aggression I believe is due to the longer days and warmer temp. So that might be it. It useully happens to a lot of my fish during this time of year.

I have only been back in the hobby now since last September (after 20+ years away!), so I'm still trying to remember some things. Kind of forgot about the yearly that these guys go through! Spring has sprung and so has my Midas!

Update: 7/6/10

I have dealt with my Midas being so aggressive, that I wore gloves to do water changes because he would bite and just latch on and shake. I had to physically push him away and show dominance so that he would back down and let me clean his tank otherwise he would just keep on biting. He also stopped eating his pellets during this time period. I was giving earth worms to him exclusively for the time just to keep him fed, because he would not touch anything else.

Well now after about 3 weeks he has mellowed. He no longer attacks me during water changes, started eating pellets again, and is his friendly little self again. One funny change now, is his choice in food. Before the breeding rage he only ate floating Omega One pellets. Now he wont touch these and only eats sinking NLS pellets. Go figure that he would pick the more expensive stuff!

Could aggressive fishes tell the difference before devouring processed foods?