harima007: can make it more details like ur tank size, any plant, light.....etc. wat color is ur guppies? is it the lighting is too strong? wats ur water ph value? any symtoms of sickness? u can try to put some salt and ketapang leaf (if u dont mind the color wil change to a bit brownish)  [5gallon to 1 tbs salt]. wat food u feeding them? i feed them with bloodworm, flakes food.   

harima007: i think u can feed them with tubiflex if u wan, rm1 per pack, 1.5' tank then i think u can put half table spoon of salt in it, then c how they doing for 1-2 days, if stil the same, then put in another half table spoon of salt, dont worry, it wont kill ur guppies. do u change the water? how often?? the best is around 1 week change 30-40% of water, and if u can, try to put some live aqua plants there, guppies like it very much. do they hv clamp tail? age the water for 2-3 days b4 u use it. ketapang i hv no idea where to get in ur area, but i hv a few ketapang trees in front of my house    the best is give them llive food then color wilb very nice, but u hv to bear the risk tat they might get parasite n desease too    correct me if i am wrong all sifuu. thnxx