Arguments for fish sentience have difficulty with the philosophical zombie problem. Progress in AI has shown that complex learning, pain behavior, and pain as a motivational drive can be emulated by robots without any internal subjective experience. Therefore, demonstrating these abilities in fish does not necessarily demonstrate that fish are sentient. Further evidence for fish sentience may come from optogenetic studies of neural networks in zebrafish. Such studies may show that zebrafish have neural network patterns similar to those that correlate with sentience in humans. Given the present uncertainty regarding sentience in fish, caution should be applied regarding the precautionary principle. Adopting this principle may cause distress ...