TOP 10 NANO PREDATORS (AND HOW TO KEEP THEM PEACEFULLY)
What Are Nano Predators?
Nano predators are small fish—usually under 2 inches—that exhibit natural hunting behaviors. These species may target tiny invertebrates, fry, worms, or micro-crustaceans, but they are far from dangerous when kept correctly.
They are ideal for:
- Planted nano tanks (5–20 gallons)
- Species-only setups
- Hobbyists who enjoy unique behaviors
- Microlive-food cultures (like baby brine shrimp or daphnia)
Nano predators are not “aggressive fish.” They simply follow their instincts and can be kept peacefully with the right tankmates—depending on the species.
Top 10 Nano Predators (Ranked for Beginner-Friendliness)
1. Pea Puffer (Carinotetraodon travancoricus)
- Size: ~1 inch
- Tank: 5 gallons for 1, 10 gallons for 3
- Temperament: Curious, nippy, bold
The iconic nano predator. Pea puffers hunt snails and worms, show intelligent behavior, and interact with their keepers. They must be kept with caution—ideal in species-only tanks unless tankmates are extremely quick or armored. For deeper care, see our full pea puffer article on stocking and compatibility.
2. Scarlet Badis (Dario dario)
- Size: ~0.8–1 inch
- Tank: 5+ gallons for a male; 10+ for a small group
- Temperament: Peaceful but predatory toward microfauna
One of the most beautiful nano predators. Males show brilliant red bars and spend their time stalking tiny prey like copepods, daphnia, and worms. Best kept with peaceful nano species that won’t compete for food.
3. Clown Killifish (Epiplatys annulatus)
- Size: ~1.2 inches
- Tank: 5+ gallons with floating plants
- Temperament: Peaceful surface predator
These tiny, colorful “rocket-tail” killifish feed on wingless fruit flies, insects, and micro-crustaceans. They rarely bother tankmates except newborn shrimp.
4. Leopard Danio (Danio kyathit “Orange” or “Green”)
- Size: 1.5 inches
- Tank: 10 gallons minimum
- Temperament: Active micro-predator
This energetic nano fish hunts small worms and insects. Safe for community tanks with fast companions.
5. Sparkling Gourami (Trichopsis pumila)
- Size: ~1.5 inches
- Tank: 10 gallons
- Temperament: Peaceful but predatory toward fry
Sparkling gouramis display subtle hunting behaviors, picking at microfauna and tiny crustaceans. Their croaking and buzzing sounds make them a true oddball favorite.
6. Bumblebee Goby (Brachygobius spp.)
- Size: 1–1.5 inches
- Tank: 10 gallons
- Temperament: Territorial bottom-hunter
Brightly patterned gobies that pick at tiny live foods. Many species prefer brackish water, so research your variety carefully.
7. Dwarf Gourami (Trichogaster lalius & related)
- Size: 2 inches
- Tank: 10–15 gallons
- Temperament: Semi-aggressive, territorial
Though slightly larger, dwarf gouramis are natural hunters of small insects and worms. They are best kept singly except in larger planted tanks.
8. Least Killifish (Heterandria formosa)
- Size: 0.8 inches
- Tank: 5–10 gallons
- Temperament: Peaceful micropredator
One of the smallest livebearers in the world, these fish hunt infusoria and tiny crustaceans. Safe with shrimp—except for newborns.
9. Exclamation Point Rasbora (Boraras urophthalmoides)
- Size: ~0.8 inches
- Tank: 5+ gallons
- Temperament: Shy but predatory toward microfauna
These tiny rasboras eat microorganisms and insect larvae. They are incredibly peaceful but will hunt shrimp babies.
10. Asian Stone Catfish (Hara jerdoni)
- Size: ~1.3 inches
- Tank: 10 gallons
- Temperament: Peaceful ambush predator
A tiny, flat-bodied catfish that lies in wait for small worms and crustaceans. Perfect for dim, cool-water nano tanks with sand substrate.
Feeding Nano Predators
Most nano predators will not thrive on flakes alone. You must offer small, protein-rich foods:
Best Foods
- Live or frozen baby brine shrimp
- Frozen daphnia
- Copepods and microworms
- Bloodworms (for larger species)
- Grindal worms
- Bladder or ramshorn snails (for pea puffers)
Feeding Tips
- Feed small amounts twice daily for active predators.
- Use a turkey baster to target-feed shy species like Scarlet Badis.
- Offer live food 2–4 times per week to encourage natural hunting.
- Always remove uneaten food after 5–10 minutes.
Tank Setup for Peaceful Nano Predators
Successful nano predator tanks rely on thoughtful aquascaping and stable parameters.
1. Provide Dense Plants
Predators feel more secure in heavily planted aquariums. Use:
- Java Fern
- Cryptocoryne
- Bucephalandra
- Floating plants
2. Break Line of Sight
Use hardscape such as Seiryu, Dragon Stone, or Spider Wood to reduce aggression. For inspiration, see our aquarium hardscape guide.
3. Use Gentle Filtration
Most nano predators prefer low-to-moderate flow.
4. Maintain Stable Water Parameters
Use the ranges described in our water parameter guide.
Tankmates: What Works and What Doesn’t
Safe Tankmates (Depending on Species)
- Chili Rasboras
- Ember Tetras
- Kuhli Loaches
- Nerite Snails (except with pea puffers)
- Amano Shrimp (except with puffers and badis)
Tankmates to Avoid
- Slow-moving fish (bettas, gouramis—if pairing with puffers)
- Very small shrimp (predators may eat babies)
- Fin-nippers and fast competitors
Stocking Plans That Actually Work
5-Gallon Tanks
- 1 Pea Puffer (species-only)
- 1 Scarlet Badis male + shrimp (if well-planted)
10-Gallon Tanks
- 3 Pea Puffers (1 male, 2 females)
- 6 Sparkling Gouramis
- 8 Clown Killifish
20-Gallon Tanks
- 6–10 Scarlet Badis in a planted setup
- 12 Least Killifish + shrimp
- 6 Stone Catfish + micro rasboras
Common Beginner Mistakes
- Assuming nano predators are community-safe. Some species must be kept alone.
- Using strong flow. Most prefer gentle movement.
- Feeding only flakes. These fish need live or frozen protein.
- Overstocking small tanks. Nano predators are sensitive to ammonia.
- Mixing species with conflicting behaviors. Research is essential.
Takeaway: Small Size, Big Personality
Nano predators offer some of the most fascinating behaviors in the aquarium hobby—from stalking and ambushing prey to interacting with keepers. With the right tank setup, stable parameters, and species-focused care, these miniature hunters can be peaceful, thriving stars of your aquascape. Choose a species that fits your tank size and feeding habits, provide plenty of plants and hiding spots, and enjoy the natural behaviors these incredible fish bring to your aquarium.
To design a nano predator habitat that feels natural and balanced, explore our aquascaping beginner’s guide next.
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