Molly fish shaking..shimmies?

Hello all..ok so my dalmatian mollies are shaking their bodies side to side when they are still..they will swim around fine but just relaxing they look like they are have a seizure or something..they eat fine, they just cant stop shaking around..i cleaned the cistern today..all new marine with aquarium salt and water conditioner..but they hold been doing this the last day or so and it seem to be getting worse..and also sometimes they will swim around really fast up and down the side of the tank..i think they may be dying or something..what should i do?? i hold only had them like 4 days..i get them at walmart..i dont want them to die..they didnt cost but like 2.17 or so but still..i have gotten attached to them already..also i know i put too much aquarium salt within the tank is a one gallon and i put a teaspoon full or so..but then i realize that is for a 5 gallon tank..i need facilitate please!
They have a parasite and you can do a few things to take care of this. Since they are molly's and molly's can bar a level of salt very close to brackish water levels easily I would buy a hydromiter (they're cheap) and see the salt level up to almost full marine water level and leave it at that plane for 3 weeks. Increase this level slowly over the course of 2 days. Estimate how much you need and just do this every few hours not counting dark time. Make sure you increase the surface water circulation because you want to increase the temperature to 82 degree and need a high level of marine circulation to counter the lower oxygen level due to the higher temperature. Don't buy from this store again and well-mannered luck.
Your tank is not cycled,it looks bad for the fish. Shimming is a sign of distress within Mollies. You should do a lot more research before replacing the fish that you lose.
Some things you will learn ----1 gallon is too small for 4 Mollies- never do a 100% marine change --- cycle a tank before adding up fish --- you'll need a larger tank for anything but 1 Betta --- the first thing a origination aquarist should buy is a book --- and lots more.
Answers:    Mollies are very tolerant to water that has a better salt content. Many will suggest that they actually live better and smaller amount prone to disease in brackish water. If the shaking is done by the females, then near is a good chance you may have a pregnant fish. In the precipitate stages of pregnancy, they will show really odd behavior. They will do a shake, they will race around the tank and they may even bump into objects within the tank or even bump into the sides of the tank itself. If you have females, this may be the problem.

To check whether you have females: The Anal fin (unpaired, single fin on the bottem rear of the fish) on females will be short and triagular in shape. On males, the fin is longer and thinner; nearly tubular in shape. You should also look up the term 'Gravid Spot.'

I would not use a one gallon tank for anything other afterwards a birthing tank. If you have the option of going near a bigger tank, then do so.

Mollies are not tolerant to higher level of nitrates as many newer tanks that aren't cycled as they should be. Use much caution near smaller tanks. Think about getting a minimum of a ten gallon tank whether you plan on keeping fish of any species other than a betta.

Good luck.
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