dalmation molly with orange spots, acting strange

kerrid

AC Members
Mar 10, 2007
230
0
0
Boston
20g tank:
1 neon tetra(three died yesterday)
2 mickey mouse platys(also acting strange)
1 small pleco(temporary home)

ammonia 0
ph 7.6
nitrite 0
nitrate 5
temp 74 (i know its low, im buying an adjustable heater today)

when i came home from work today the molly was on its side on the bottom of the tank. i noticed he had orange spots on him also. yesterday he was swimming like crazy all around the tank and now it looks like hes dying. i went to catch him but i couldnt. i didnt want to stress him any more than possible so i stopped.
also, the mickey mouse platys lie on the bottom of the tank. they're not as inactive as the molly, but it does seem like theres something wrong. i thought i saw some white spots on one of the platys' tails but im not sure. everytime i try to get a closer look they swim away from me.
the tetra is acting the way he did when i first got him and the pleco doesnt do anything anyway.
could the deaths of the three tetras yesterday have brought some disease into the tank? am i doing something terribly wrong that's causing my fish to die?
:help:
 
how long has your tank been set up?

the orange spots may be velvet:
symptoms may resemble white spot. the skin looks like it has been dusted with yellowish powder.

you need to raise your temperature to between 75 and 80 degrees and get a medicine for velvet.
 
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