Here's a breakdown:
* Most fish can't see red light: This is because red light wavelengths are absorbed quickly by water. So, at even relatively shallow depths, red light doesn't penetrate well.
* Some deep-sea fish have evolved to see red light: Some fish living in the deep ocean have developed visual systems sensitive to red light, allowing them to hunt or communicate in the dim, red-filtered environment.
* Fish in aquariums may see red light: If you shine a red light on fish in a tank, they might see some of it. This is because the water in the tank is typically clearer and doesn't absorb as much red light.
So, the answer is not a simple yes or no. It depends on the specific fish species and their environment.