Territorial problems.

I spy Earl hovering with graceful ease at the top, his crown place supreme. He looks over his kingdom with chin high and a leery eye, ready to pounce on his people -- intruders into his house, taking up his precious space, laying their waste on his precious stone floor, eating the food that was provided especially for him by the gods who provide air to breathe, light to see -- how generous need he be, after all. This is his land -- what's rightfully his, by golly! He commands the high seas!

And there! A flash of neon red. The Red Baron: Monty by name, is it, that's what they call him. A small and insignificant creature in Earl's opinion, with ne'er the size nor will of this worldly crown prince. Eat my food, dare he?? Earl's instincts flash and he's off in a rage!

Colors explode round and around the tank as Earl bullies Monty back into the hole he belongs in. Shivering and cowering in the darkness of stone shadows, Monty admits temporary defeat. Earl harrumphs and turns mightily away, ready to arrest another foul plot-in-progress.

Meanwhile, hunger drawing out his desperation, the Red Baron slides out yet again of his hiding place and circles around the opposite side of the stone pillar, out of King Earl's sight, out of mind... if he can only maintain his stealth. Monty calls out to the gods, and the they respond, creating a distraction of a mirage! A large finger appears and seizes Earl's fascination while Monty captures another piece of flakemeal, and darts back to his hole, what a treat! Praise the lord! Starvation escaped yet another delicious minute.

Earl suspects. He circles around the pillar, giving a threatening jab or feigned-attack, and Monty is still ever the prisoner of a place that is also rightfully his. If only he weren't so small or brainless...

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The never-ending story of my fish, Earl (Tiger Oscar, 5") and Monty (Blood Parrot Cichlid, 2.5").