my eels love earthworms,ghost shrimp, and live tubaflex. You could buy them at a gardening center....I don't know about in India though.
TKOS said:No the pet store will probably sell a salt mixture for marine tanks/ saltwater setups. That is the salt you need to use as it has all thebuffers etc... needed to make a brackish or marine tank. Don't think of brackish as salty freshwater but as weaker saltwater (IMO). Something to measure specific gravity is really needed at this point, either the store can do it for you or else they can sell you a device to do it. The plants will die as the salt increases so be ready to take out any dying plants so they don't foul up the water. Increase the SG of the tank by 1.002 per week to let the eel adapt to the changes. Hopefully that will help it before things get too late.