Help! My fishes is stress

[Zhi Cong]

I've numbers of neon tetra in my 15gallon aquarium tank, and they are doing fine althought its nearly overcrowded. After i turn off the light i did notice the tetras being stress up and swim recklessly, and even tried to jump out of the tank. I'm quite sure the stress is due to the sudden of darkness. When i got back home, my neon tetra turn pale/loss color and hide at corner of the tank.

My question is how can I manage my room lighting and which product is recommended for me to buy to prevent stress for my fishes?

[Urban Aquaria]

To reduce the sudden change in light on the aquarium, try to adjust the active light photoperiod to start and end when there is still some daylight illuminating the room (ie. morning to afternoon, like 9am to 5pm type) so that the change is less abrupt.

Do note that if an aquarium tank has been in darkness for a while, tetras will naturally turn a pale color when resting to match the darkness (since there is no need to show bright colors anymore, it's a camouflage against predators while they rest), that is a normal characteristic and isn't due to stress. Their bright colors will gradually return automatically when the light is switched back on for a while.

On the otherhand, if your aquarium light has been on for a while and the tetras are still pale in color, then that is a sign of stress and you should check your water parameters.