Here is some information about them and they are considered freshwater fish. They are say that you add salt for better health and when you want to breed them...
Common Names: Glassfish
Indian Glassfish
Synonyms: Ambassis ranga
Chanda ranga
Pseudambassis ranga
Family: Ambassidae
Category: Other_Freshwater_Species
Distribution: Asia; India, Burma, Thailand.
Main Ecosystem: River; River
Temperament: Peaceful; Peaceful and timid. Once settled in they become a little territorial.
Diet: Carnivore; Carnivore
Care: Feed with flakes and small live foods. Live food should be feed at least once per week. Add some salt the water for better health. Keep some larger broad leaved plants in the tank and rocky hiding places.
pH: 7.0 - 8.0
Temperature: 20C - 30C
(68F - 86F)
Hardness: 10 - 20 dH
Potential Size: Male: 8cm (3.1")
Female: 8cm (3.1")
Water Region: All; All
Activity: Diurnal; Diurnal
Gender: Males have a blue edge to their fins (see photo).
Breeding: Not Hard. The Glass Fish should be kept in water with two teaspoons of salt per 12 litres for two to three months prior to breeding. To instigate breeding place the tank in a place where it can receive morning sunlight and do a partial water change with fresh water (no salt) while raising the temperature to 26-28°C. The eggs are laid on broad leaved plants. Though the Glass Fish is easy to breed, their offspring is quite hard to raise.
Variants:
Comments: Best kept in a small school. Othen the Glass Fish is injected with an artificial dye to increase their sales.
From
http://www.fishprofiles.com/files/profiles/275.htm