Unfortunately, aggression can start up between uros who have lived peaceably together for years. Their sex doesn't necessarily have anything to do with it, either. Sadly, you're probably right - they need to be separated permanently.
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Torey
Eugene, Oregon, USA
1.2 Saharan Uros (Joe, Arthur, and Hitch)
3.0 Mali Uros (Spike, Turtle, and Tank)
1.1 Ornate Uros (Scuttlebutt and Shazzbot)
1.3 Collared Lizards (Ripcord, Thiamine, Riboflavin, and Niacin)
1.0 Green Anoles (Sprocket)
1.1 Chubby Housecats (Roscolux and Jenny)