Sleep
Only a true enthusiast would go to a web page titled 'sleep'. This page is about environments, what different fish need of them, running up to and including the nocturnal cycle.
Details...
Topics covered are lighting, water turbulence, feeding, night time deaths, fry lights and how to watch them at night, in night watch.
LIGHTING
It is somewhat abrupt and unnatural to pitch an aquarium into pitch black darkness. When given the opportunity, fish wind down their activity levels. They retreat to areas they feel comfortable for sleeping, or areas which agree with the manner in which they sleep. Staged lighting, to put them to sleep (and especially to wake them up) is achieved with more than one light circuit and a couple of timers (running a transition 'night' light and main lights). A 10 minute overlap is enough for them to wake and prepare for the bright lights, or to wind down to their respective sleeping zones.
TURBULENCE
During the day, fish will migrate to the area of the tank which best agrees with their needs, some playing in the output of the filter, others finding a quieter spot elsewhere. The same occurs at night, though their individual needs might vary. The key here is to provide enough variety that every occupant can find an area which meets their requirements. Lots of breakwaters can be used, such as plants, rocks and driftwood, so there is a turbulent side, closer to the filter output, and a quieter zone on the opposite side.
FEEDING
Many nocturnal fish are not, when placed in an aquarium, but some stick to their nature. Night time is when some algae-eating plecos come out of their caves, so if your tank is relatively algae free, then dropping in a nightly algae disk is a good idea. If your night time denizens are more carnivorous (Eels, Knifefish, some catfish, some plecos), then a meaty offering is a necessity, unless you want them to be tempted by their tank mates. The very beautiful Black Ghost knifefish does not really have what looks like to be a very small mouth. If you consistently drop your night time food offerings in the same location, you will find that the fish locate them much faster, to the extent that they are almost there waiting for it.up
DEATH
Fish vanish overnight, sometimes without leaving a trace. Many predators are not inclined to engage in frantic chases for tiny tetras during the day, but under the cover of darkness, tiny sleeping fish and a little stealth changes everything. Angelfish are excellent hunters, using their narrow profile to allow them to sneak up behind a sleeping victim. Others use a mild electric charge to locate their prey at night. Blind cave characins, have no eyes so never need any light, but in complete darkness they have quite an advantage.
FRY LIGHTS
For parental spawners (ie: cichlids) nightfall brings extreme danger. They are perfectly capable of defending their fry against all dangers, but in total darkness, there are many fish which can sneak in and consume their fry. Provide them a small nightlight so they are able to maintain a vigil. In nature, they would have moonlight, and would have selected a more secluded spot.
NIGHT WATCH
While fish have colour perception similar to our own (according to the anatomy
of their eyes), there are frequencies of light which they do not register. I haven't
tried it, but I've read that actinic light or a black light is outside their visual
acuity, so such a light would allow the hobbyist to observe the nightly activity.
Keeping the room outside the aquarium in total darkness will cause you to be invisible
to the fish, and they will behave as if your are not even there. You might be
surprised by what you see. Some tanks have considerable nocturnal activity, and
the colour changes in sleeping fish can be quite unusual.
|
