Fish loosing colour and developing white spots.?

[boyd R]

I have a fluval 125 litre tank. fluval 3 filter. and a appropreate fluval heater. in the tank i have 2 plecs, 4 glowlight tetras, 5 rummy nose tetras, 2 swordtails and rainbow fish. the tetras seem to be the worst and have lost alot of colour and are not swimming properly. also on the rummy nose tetras i can see tiny white spots. ive had the glowlights and the swordtails for over a week no problem. but now that i have introduced the plecs rummy noses and rainbow fish. thr tetras are loosing colour. and this may sound insane but one of the glowlights is completely missing it was very pale and was always near the surface. now it is completely gone i cant find it anywhere. help please!!!!
I have a fluval 125 litre tank. fluval 3 filter. and a appropreate fluval heater. in the tank i have 2 plecs, 4 glowlight tetras, 5 rummy nose tetras, 2 swordtails and 4 rainbow fish. the tetras seem to be the worst and have lost alot of colour and are not swimming properly. also on the rummy nose tetras i can see tiny white spots. ive had the glowlights and the swordtails for over a week no problem. but now that i have introduced the plecs rummy noses and rainbow fish. thr tetras are loosing colour. and this may sound insane but one of the glowlights is completely missing it was very pale and was always near the surface. now it is completely gone i cant find it anywhere. help please!!!!