Glass Knifefish (Eigenmannia virescens) is an intermediate-level freshwater fish that needs at least 55 gallons and 75-86°F. A translucent, nearly tail-less fish that swims with an undulating ribbon-like fin and senses its surroundings with a weak electric field. It is nocturnal and shy in bright light, so keep it with calm tankmates its own size or larger and give it shaded hiding spots.
Care facts at a glance
| Scientific name | Eigenmannia virescens |
|---|---|
| Family | Sternopygidae |
| Origin | South America |
| Adult size | 7 in |
| Minimum tank | 55 gallons |
| Temperature | 75-86°F |
| pH | 6.7-7.4 |
| Temperament | Peaceful toward similar-sized fish, but will eat very small tankmates |
| Social behavior | Small group of its own kind |
| Swim level | Mid to bottom |
| Difficulty | Intermediate |
| Diet | Carnivore: frozen bloodworms, brine shrimp, small sinking pellets |
| Typical lifespan | 8-10 years |
Quick tips
- Keep several together rather than just one.
- Provide dim lighting and plant cover or driftwood to hide in.
- Avoid tankmates small enough to be eaten after dark.
San Diego water
Prefers softer, more acidic water than San Diego's tap (pH roughly 7.6-8.6, hard). Most keepers blend tap with RO/DI water or use a remineralized RO/DI supply. Learn the numbers in our San Diego tap water guide.
Before you buy
Make sure your tank is cycled (how to cycle a tank), check your numbers with the water testing guide, and use the compatibility guide to check tankmates. These are general ranges; individual fish and local water vary.
Find it at Pet Zone
Pet Zone Tropical Fish is a San Diego aquarium store with two locations. Stock changes daily, so call ahead if you are after a specific species or plant. Shop online at petzonesd.com.
4160 Convoy St, San Diego, CA 92111
(858) 987-0309
Open daily, 10am-6pm
Aquascaping, planted tanks
4266 University Ave, San Diego, CA 92105
(619) 283-1812
Closed Monday; Tue-Fri 10:30am-6pm, Sat 11am-6pm, Sun 11am-4pm
Monster fish, koi