firelord77 wrote: But a month ago, from time to time, the male began to let out a strange black "intestine" (I presume this is his reproductive organ) under his tail, and retract it. This always attracts the female who bites him on that "intestine"and won't let go until I separate them. Today she managed to hurt him by doing this, because there were a few drops of blood.

Could anyone, please, help me! I don't know what to do. Should I separate them for a while?
Unfortunately, they will either A.) need a bigger tank set up or B.) need to be separated permanently from now on (I vote for B, based on personal experience). I went thru something similar between a male & female turtle that cohabited a tank and I can tell you that the fighting is not pretty to watch. It also gets more violent as time goes on.
Many yrs ago, I had a male & female too. We always thought it was cute to watch the male court the female by fluttering his nails in front of her face, or flash his male organ when he reached puberty. At first, she didn't seem to mind & would tolerate him for hours on end without a response. Then, it was like the war of the roses!!! My larger female RES (7") would literally snap at the 4" male, sometimes breaking off one of his very long nails in the process as she chased him around the tank. One time she pulled so hard on his arm that it became sprained. Then another time, he attacked her & started snapping at her arms/legs, drawing blood. It was a constant battle between the two (very LOUD when they fought as they ran into the glass of the aquarium) and eventually I just had to let one out (to walk around my living room) during the day for 6-8 hours, then rotate with the other one that was still in the tank. The only time they were ever together in the tank was at night, when all the lights were off & sleeping. This worked out well, but it was a major pain in the [---] to constantly have to track how long a turtle has been out of the tank. Not to mention that the female was laying eggs almost 3 times a year (due to the presence of the male) and I had to constantly deal with the big mess she would either leave in the tank when the eggs would get laid in the tank & destroyed or partially eaten by her, or laid under the beanbag in the living room (!). I was constantly trying to catch the eggs before they turned into a big mess. And when she laid them in the tank, it was a mess of egg yolks in the tank, covering everything, getting in the filter media, etc. Everything needed to be scrubbed down. Changing tank water was a bucket by bucket job, very laborous, especially when you end up doing it one day, to find out that she wasn't done laying eggs, and now you have to do it AGAIN 2 days later (55 gallons!). I finally gave up the battle & gave the male to one of my friends who was looking for a pet.
As much as I hated to let him go, I knew he went to a good home, & life has been very peaceful. Now I can dedicate all my efforts to Sheba.
I will never again have 2 turtles in one tank again. No thanks. Sheba (full-grown adult of 11") keeps me busy enough!
