I was reading the question Aquarium lighting systems that follow seasonal changes? and I got thinking.
If an indoor fish tank has a heater, it probably holds primarily tropical fish. As the tropics are near the equator, there is little if any seasonal change in the heat or lighting.
If you have tropical fish, what impact if any do seasonal light changes have on the fish? Are there any seasonable variables other then light that might impact the well being of tropical fish?