Originally Posted by AnjelicaMedeiros
I don't know what's happening i bought 3 Platy fishes about a couple of weeks ago, I've been feeding them freeze dried bloodworms and some brine shrimp. I've also a Rainbow Shark and a Dragon Goby too. Their tank is between 60 and 80 F, and has been since i've put them in their, i also had the tank heated two days prior to putting them in there. I feed them about three times a day. But a couple of days ago i went into my room and found that one of my Platy's was dead ( He was deep red with a dark black spot along him) and he look kinda cyrstallized (whitish) it also looked as if a little chucnk was missing from it's tail. Now my other one ( Orange and Black) has been looking a little sick too and not swimming as much as it use too and has a glazy look to it's eyes, and it's starting to stick by the filter alot. My micky Platy looks like it's doing fine. But my Rainbow shark has also started to get white spots on it's tail and fin's and on it's head, he hides in a bush a lot, but it swims normally. I have no idea what might be happening, they were all alright for the week and a bit i had them but now it seems something is happening. I don't know the pH or nitrate levels, and have no idea how to check them either, and i don't know wether they are males or females. I need help i want to save my fish!!!
First of all sorry for your loss and welcome to the forum
There are some serious issues here which need addressing urgently.
First of all a 20F temperature difference is enormous for fish and can stress and kill them. You need to set the heater to a temperature suitable for the fish you are keeping.
I suspect your tank is NOT cycled...look here
for an article on cycling your aquarium. To know when your cycle is complete and water parameters are good for your fish you MUST acquire a testing kit. API Freshwater Master Liquid Test Kit, is highly recommended.
The white spots on your fish are a disease called ich, which is a parasite. Have a look here
for information on ich and treating it...This usually involves either adding commercially available ich medication or adding salt, one thing that would be extremely beneficial though, is if the fish can take the temperature bump it up to 80F this will help the life cycle of the ich parasite complete quicker.
In short you MUST get a test kit or have your LFS (Local Fish Store) test your water and give you EXACT numbers for ammonia, Nitrite and Nitrate, NOT yes its good or you have slight ammonia, NUMBERS only.
I would highly recommend that you look into getting an ich medication as soon as possible.
I regret to inform you though that with such a "young" tank, it may be too late to save the fish, ammonia and Nitrite are extremely toxic to fish and if your tank is not cycled then this will be already having an effect on the fish. With ich present as well, it may simply be too much for the fish.
Ich can materialize in many ways and usually attacks fish with weaken immune system caused by stress or other factors, the other factors here being your tank is unlikely to be cycled.