Please Please Help! What Is Happening?!

[comocrayfish5]

the other day there was a dead fry in my tank, this is usually that i might find a dead fry; i can see it coming- they get very thin and die. i did question the fish in my mind because inside it mouth and throat, i guess, was all red. i thought nothing of it at the time until i saw right mow that my "champion" molly (the biggest molly since about 2 months of age) had this weird 'red mouth throat and gills' and then i look at all the other fry, and there is a thin dying one with the same thing. i took some pics, they are not the best but you get the point. the weird thing is that my champions 'red' problem disappeared as if he swallowed the stuff, though i did see it later in the day then it was gone again...

i did put some salt in the tank and i did a 4 gal water change (20gal tank) earlier today before i noticed the other fish with it.

PLEASE help! i have had these fry for over 7 months (ranging from 1-7 months) and they mean the world to me!!! i even watched some being born- which if you have watched it happen, you will understand my love for the fry. i also have several different kinds in there and i would hate to loose them!!!!!!!


Thank You!!!!!!!!!
this is Not my champion, this is the dying fish i found that has it real bad.

 

[AquaticHamster]

Oh dear. He looks pretty bad. Dalmations are my favorite kind of molly too. I can't say I know whats going on, but I do hope they live. Best of luck!

 

[This Old Spouse]

Did you have brackish water before you put salt in the tank? Mollies prefer it, but I don't know if this is what's causing the problems.

 

[McCool]

What is your water like? Stocking?
Could it be an ammonia problem? Ammonia turns their gills red, though I'm not sure if it would be on their mouth like that.

 

[comocrayfish5]

Did you have brackish water before you put salt in the tank? Mollies prefer it, but I don't know if this is what's causing the problems.

the water was not brackish before putting salt in.

What is your water like? Stocking?
Could it be an ammonia problem? Ammonia turns their gills red, though I'm not sure if it would be on their mouth like that.

my water: (the words are just what the chart says under the #)
nitrate: 20 (safe) (i keep trying to lower these and its getting better-was never at 'danger' to begin with)
nitrite: 0
hardness: 75 (soft)
alkalinity (kh): 80 (moderate)
pH: 7.2

there is about 65 or so fry in the 20gal tank. they range in size by a lot. i have some 1-ish month old guppy fry all the way up to 7-ish month old molly fry which are probably smaller than they are supposed to be at this stage. i also have some sword t. fry, feeder guppy fry (+ 3 small adult feeder guppy). platy fry, and small but beautiful yellow snakeskin, a tequila sunrise/snakeskin, and a red guppy in there too (all these fry are smaller than the molly fry.)

after i am done cleaning all my tank this weekend i will do several water changes throughout the week in the fry tank