By Donna M. Recktenwalt
Most killikeepers have at some time observed that the same fish, viewed under different lighting conditions, can appear entirely different. Sunlight from a window can transform a usually dull looking fish into a spectacular one; a fish that looks bland in a show tank can suddenly turn beautiful in a flashlight beam.
But what is the best lighting for viewing killifish?
“Many killies get more colorful in subdued light, for some reason,” observes Wright Huntley. “I have SJO in my bright plant tank … and they look washed out all the time. Brothers in an overgrown, darker Salvinia-covered tank look brilliant. Survival mechanism? I don’t know.”
Some fish need to be seen in reflected light (from the side) to show their true beauty, particularly iridescence. Some fish even seem to vary in coloration by time of day. Some killifish only develop their best colors when they receive significant daylight over long periods.
However, by choosing a good light source, and utilizing a few simple techniques, fish color can be enhanced. Dark substrates and backgrounds help, as do plants, by providing more security (comfort) for the fish, and by providing more visual contrast to the viewer. Many fish (killifish in particular) never do become completely comfortable over light-colored substrates. The use of color enhancing foods can also help.
For best appearance, a combination of ‘sunlight’ and ‘daylight’ tubes seems to work well. Cool white bulbs have too much green, subduing red and blue coloring. Plant and aquarium bulbs may give good color, but you often need a cool white bulb to bring up the brightness, and the greens.
Incandescent lights show killies off fairly well, but produce a great deal of heat. Compact fluorescents with a tri-phosphor work well too, but do require good ventilation to prolong the life of the ballasts.
— G.C.K.A. Newsletter, July 1999 and March 2002.