Following up on observations of changing fish behaviour when either lighting or flow rates are changed, here we take a look at what happens when the lights turn off.
The video shown starts after the Kessil A80 light has been on for nearly 6 hours, the typical photoperiod for the current setup. The tetras and barbs are towards the bottom right portion of the tank, as they have been for almost the whole day. Once the lights turn off (automatically) they become more adventuresome, and expand their range to the upper reaches. To see whether this was a temporary reaction to the change in lighting the video also skips ahead to 30′ after the lights have turned off, and the fish are behaving in about the same way, suggesting is it the state of the lighting rather than the change in lighting that is driving their behaviour.
More thoughts after the break…
Lights turn off at 0:30
30 minute time jump to low flow at 1:25
High speed flow at 1:57