Tropical freshwater fish do not have to be large and colorful to be desirable. Unique features in body and behavior attract hobbyists to keep various species of fish. One such fish is the virtually colorless, yet attractive, Indian glassfish (Parambassis ranga). The Indian glassfish (aka glass perch) is a relatively deep-bodied, laterally compressed fish that can grow to 3 inches. While the head and belly are silver, the rest of the body is transparent, so the prominent backbone and other bones are visible. This glassfish has a double dorsal fin, a long-based anal fin and a large double-lobed caudal fin, all of which are transparent. It has a pale green iridescence, particularly over the dorsal area, which makes for quite a pretty fish. Young male and female fish are very similar, but when mature, males tend to have slightly larger dorsal and anal fins, which are edged in gray.
The Indian glassfish has a fairly widespread distribution that extends from India into Pakistan and also to parts of Southeast Asia. For the most part, it comes from a freshwater habitat, though sometimes it is also found in brackish water. Rivers and lakes in India are generally soft and acidic (dH 2 to 8 and pH 5.5 to 7). Glassfish live in shoals and prefer a well-vegetated habitat that provides shelter. They feed primarily on small live foods, such as crustaceans, insect larvae and worms.
Because of the myth that Indian glassfish prefer brackish water, many fish stores set them up in brackish conditions (specific gravity 1.004 to 1.008). This limits the popularity of this pretty little fish, since brackish aquariums are set up less frequently than freshwater aquariums. This fish also does well in neutral, soft freshwater.
The Indian glassfish is usually found in shoals in the wild. Keep small shoals of six or more fish, as this gives them a sense of security and well-being. Single fish or a pair will be nervous and hide. Before making the purchase, ask the fish store about the water. The salinity of the water will dictate how you need to proceed when setting them up in your home aquarium. Next, ensure that the fish are healthy and swimming well with their fins extended and not clamped. Ask to see the glassfish feeding, which will also give you an indication of what foods to purchase. If they are feeding well, they are ready for purchase. Before buying your shoal, have their aquarium ready. This fish species does best in an aquarium that is relatively mature rather than a new one that has just been set up.
In a Freshwater aquarium
If the glassfish are in brackish water at the tropical fish store, you will need to slowly acclimate them to freshwater. This is best done in a separate, fully functional quarantine tank containing brackish water. Change the salinity over a week or two, with daily freshwater changes of about 10 to 15 percent.
A 30-gallon aquarium is suitable for keeping a small shoal of Indian glassfish. Water should be near neutral, yet on the soft side (pH 7 and dH of 4 to 6). Use an external canister filter to provide a current of water and to keep nitrogenous wastes (such as ammonia and nitrites) low. Regular partial water changes will also help remove nitrates. Plant Southeast Asian aquatic plant species in a 3-inch bed of small-sized smooth gravel. Plant taller plants around the back and sides and shorter species in the foreground. A few pieces of bogwood provide a nice touch while providing cover for bottom-dwelling fish. Provide light for the plants with fluorescent tubes (45 to 60 watts), and add a heater to maintain the temperature at around 77 to 81 degrees Fahrenheit.
Suitable freshwater tankmates can include six colorful harlequin rasboras (Trigonostigma heteromorpha) and six zebra danios (Danio rerio). These fish add a nice contrast to the colorless glassfish, as they also have different body forms, different swimming styles and habits. Four or more chain loaches (Yasuhikotakia sidthimunki) or other small loach species fill in the bottom areas of the tank. While the rasboras, danios and loaches will happily take good-quality flake foods, glassfish need to have live food or frozen equivalents, such as Daphnia, mosquito larvae, brine shrimp and bloodworms. In the community aquarium, glassfish should soon come around to taking flake food.
In a Brackish aquarium
If the glassfish are in brackish water at the fish shop, then they can be placed directly into your mature brackish tank once it is ready for fish. Glassfish from freshwater aquariums will need slow acclimatization to brackish conditions in a separate quarantine tank, as mentioned earlier.
If you are converting a freshwater tank to brackish, conversion to brackish conditions needs to be done slowly, as the bacteria in the canister filter need slow adaptation to saltwater conditions. Use marine salt rather than aquarium salt or table salt, which is just sodium chloride. While freshwater has a specific gravity of 1.000, and full marine water is about 1.020, the brackish water for this setup should fall in the range of 1.005 to 1.010, which is roughly equivalent to 1 tablespoon of marine salt per gallon of water. Dissolve the marine salt in water before introducing it to the aquarium. When converting from freshwater, start with 10 tablespoons in the 30-gallon aquarium per week, and reach the required specific gravity within three weeks.
Use a hydrometer to get an accurate reading of the specific gravity. Replace evaporated water with freshwater (no salt added).
Again, a 30-gallon aquarium is a suitable size for a community of brackish fish. The selection of brackish tankmates is limited compared to what’s available when it comes to freshwater fish. For the substrate level, add a peaceful pair of colorful orange chromide cichlids (Etroplus maculatus). Orange chromides only reach an adult size of 3 inches, and they are relatively peaceful, even if they do decide to spawn in the aquarium. They will care for their fry, and they should not trouble the glassfish that occupy the middle and upper waters. An alternative to orange chromides for the substrate level would be six to eight bumblebee gobies (Brachygobius xanthozonus) or two to three knight gobies (Stigmatogobius sadanundio). Two or three black mollies (Poecilia sphenops) acclimated to brackish conditions can share the middle waters with the glassfish. While some of these fish will eat a good-quality flake food, they will all do best on live or frozen foods.
Only hardy plants will survive in a brackish aquarium. One that is always available is Java fern, which can either be attached to bogwood or pieces of rock. Java moss will also do well. About 45 to 60 watts of fluorescent lighting is enough for these plants. Use a high-quality heater that can withstand salt conditions to maintain a temperature of around 78 degrees.
Breeding Indian glassfish
In the wild, the Indian glassfish breeds during the monsoon season when temperatures are high and the coming rain softens the water. Ponds, lakes, streams and rivers overflow their banks, and there is a huge increase in natural live foods. When glassfish are maintained in brackish water in the aquarium, large water changes with freshwater that reduces the salt percentage may induce them to spawn, if the fish are in good condition.
Glassfish spawn frequently in aquariums, but the eggs will be eaten. To raise the young, set up a small, separate breeding aquarium filled with soft water at a temperature of around 84 degrees. Furnish the breeding aquarium with Java fern because these fish spawn on broad-leaved plants. Include a mature air-driven sponge filter that produces little water current. Female fish, which have less-colorful fins than males, should be placed in the breeding tank and fed plenty of live food for at least a week to allow them to fill up with roe. Then introduce male fish to the breeding tank at night; spawning takes place at first light. The spawning pairs scatter their eggs among the plants and should be removed once spawning has ceased (this will prevent them from eating the eggs). Add a few drops of methylene blue to prevent the eggs from being attacked by fungus.
The eggs will hatch within 24 hours, but the fry remain attached to the plants for another three to four days as they continue to develop while they feed off of their yolk sacs. When they become free-swimming, they need to feed on copious amounts of microscopic infusoria found in green water before they are big enough to take newly hatched brine shrimp nauplii. They grow faster once they get to this stage; they should be moved on to larger foods and bigger aquariums so as not to crowd other growing fry. Nitrogenous metabolites will stunt their growth, so perform frequent water changes to keep these low. When the fish are ready, your fellow hobbyists at the local fish club or even the local fish store should be happy to take some of your home-grown Indian glassfish off of your hands.
Small Indian glassfish are attractive, even though they lack color. They do well in a mature freshwater aquarium or a brackish aquarium. If kept in a shoal, their character comes to the forefront as males strut their stuff with fin-flaring displays often followed by a chase as they try to attract the attention of females. If provided with pristine conditions, and live or frozen foods, Indian glassfish should grace the aquarium for two years or more. AFI
Iggy Tavares, Ph.D., started keeping fish more than 40 years ago when he caught some wild guppies in an African stream. His passion is breeding cichlids. He also enjoys writing about his numerous experiences and is an enthusiastic fish photographer.