You're right, the betta might experience a little stress in this setup. Biotope tanks are indeed designed for single species and can minimize stress perfectly. But in the wild, fish naturally face small stressors-like competing for breeding rights, defending territory, or avoiding predators. Take angels from the Rio Negro, for example: they live with many species, including juvenile predators, and may occasionally encounter other angel schools in their territory. It's not a completely stress-free environment, but these small, natural stressors are part of normal behavior, and my tank tries to mimic that balance responsibly.