My koi's are just not seeming to be taking to my 2 15 watt fluorescents that i got with my 50gal tank... I even try to gradually lighting up the tank, first i pull my curtains then the room light 10 mins later one florescent... 5 mins later the other but it just dont seem to work.... They just sit in the front or back corner of my tank staying away from the center of the tank...and if they do decide to get from the corner they jet to the other side staying as close to the back of the tank.... I even kept the light on for a few hours and they still was in the same spot just not being active... but when that light is off with sunshine from the window there good... just energetic swimming and digging for food etc... I think i need a lower watt fluorescents?!! What do yall think????

....my opinion.......
Koi belong in ponds not tanks......