Those look like Giant Freshwater Prawns (Macrobrachium rosenbergii). Not worth Rs 400 in my opinion. I used to buy them for Rs 20 in VaranasI as feeder shrimp for my large Red Tailed Catfish. They aren't suitable for most aquariums in my opinion. I don't think you should get any.
Yeah I grew up there! Hahaha.
Your welcome .
Hmm... Well in India I always found they had really really nice looking bettas. You could try a betta with some Red Cherry Shrimp if you can find some. But I would look for a Honey Gourami personally. Then you can add some small tetras. Your tank isn't big enough to add too many types of fish. Do you have fish in it now?
Some low light plants would look nice. Do you have gravel on the bottom? And do you have a light for the tank?