Longfin Zebra Danio
Danio rerio
A flowing-finned zebra danio variant, hardy but a touch slower-swimming.
| Difficulty | Beginner |
| Min. Tank Size | 55 L |
| Temperature | 18.0–25.0 °C |
| pH Range | 6.5–7.5 |
| Max Size | 5.0 cm |
| Lifespan | 3-5 years |
| Diet | Omnivore |
| Temperament | Peaceful |
Overview
The Longfin Zebra Danio (Danio rerio) is a flowing-finned zebra danio variant, hardy but a touch slower-swimming. It is one of the most recognisable members of the danios group kept by Australian aquarists, valued for its appearance, manageable adult size of around 5.0 cm and its peaceful nature.
This guide covers everything you need to keep the Longfin Zebra Danio successfully - ideal tank size and setup, water parameters, diet, suitable tank mates, breeding, how to tell males from females, and the health problems to watch for. Rated Beginner to care for, it can live for roughly 3-5 years when its needs are met.
Natural Habitat & Origin
Danios come from the cool, clear, fast-flowing hill streams and rivers of India, Bangladesh, Myanmar and the Himalayan foothills. They are used to moving, oxygen-rich water and cooler temperatures than most tropicals, which makes them both hardy and tolerant of unheated rooms.
Understanding where a fish comes from is the shortcut to keeping it well: matching the temperature, water chemistry and amount of cover it evolved with is far more effective than fighting against its nature.
Tank Size & Aquarium Setup
Provide a minimum of 55 litres for the Longfin Zebra Danio. Because it is a shoaling fish kept in groups, floor space and swimming length matter more than height.
Use a secure, well-fitting lid (this species can jump, and labyrinth fish also need a warm layer of air above the water).
Live plants, driftwood and some shaded retreats give the fish security and show off its colours against a natural backdrop.
Mature, well-cycled biological filtration is essential before adding any fish. Match the filter's flow to the fish - moderate for most, stronger and more oxygenated for hillstream and riverine species.
Water Parameters
Keep the Longfin Zebra Danio in stable water at 18-25 °C with a pH of 6.5-7.5. It is adaptable across a moderate range, so stability matters more than hitting an exact number.
Test your water regularly: ammonia and nitrite must always read zero, and nitrate should be kept low (ideally under 20-40 ppm) with routine partial water changes. Sudden swings in temperature or chemistry cause far more illness than water that is slightly 'wrong' but stable, so always dechlorinate and temperature-match new water.
Diet & Feeding
The Longfin Zebra Danio is an omnivore and an easy feeder. A quality flake or micro-pellet forms a good staple, enriched several times a week with frozen and live foods such as bloodworm, daphnia and brine shrimp for colour and condition.
Feed small amounts once or twice a day - only as much as the fish clears in a minute or two - and consider one fasting day a week. Overfeeding is the single most common cause of pollution and disease in home aquariums.
Temperament & Tank Mates
The Longfin Zebra Danio is an excellent peaceful community fish. It mixes happily with other calm species that share its temperature (18-25 °C) and pH (6.5-7.5) needs, are too large to be eaten, and are not large enough to eat it.
Crucially, the Longfin Zebra Danio must be kept in a group of at least 6 of its own kind (8-12 is better). A proper shoal is calmer, bolder, more colourful and far less likely to pester other fish - skimping on numbers is the most common cause of stress and nipping.
Breeding
The Longfin Zebra Danio is an egg-scattering species. To breed it, condition a group on live and frozen foods, then move them to a dim tank with fine-leaved plants or a spawning mop; the parents scatter eggs and will eat them, so remove the adults after spawning.
Even if you do not plan to breed it, understanding this behaviour helps you recognise it in the tank and respond appropriately - for example by adding cover for fry or by giving a guarding pair some space.
How to Tell Males from Females
Female danios are noticeably rounder and larger-bodied, especially when carrying eggs, while males are slimmer and often a little more intensely patterned.
Common Health Problems
Like most aquarium fish it is susceptible to white spot (ich), fin rot and fungal infections, almost always triggered by stress or poor water quality. Quarantine new arrivals for 2-4 weeks to keep your main tank disease-free.
Prevention is far easier than cure: keep water pristine, avoid overstocking and overfeeding, quarantine new arrivals for two to four weeks, and watch daily for early warning signs such as clamped fins, loss of appetite, flashing (rubbing on objects) or laboured breathing. Caught early, most problems are very treatable.
Is the Longfin Zebra Danio Right for You?
The Longfin Zebra Danio is a rewarding choice for beginners and experienced keepers alike, as long as you can provide at least 55 litres, water at 18-25 °C and pH 6.5-7.5, the right diet and a proper group of its own kind.
Get those basics right and you will enjoy a healthy, colourful Longfin Zebra Danio for around 3-5 years. For tank planning, try our free aquarium tools, and browse our fish, plant and disease guides to build the perfect community.