Temperature
Red Comet Swordtails are hardy tropical fish but thrive best in stable, warm conditions.
- Range: 72–82°F (22–28°C)
- Optimal: 75–78°F (24–26°C)
- Stability: Sudden temperature drops can weaken their immune system.
💡 While they tolerate slightly cooler water than some tropical species, they should not be kept in unheated tanks with fluctuating temperatures.
pH Level & Hardness
Swordtails prefer slightly alkaline, mineral-rich water.
- pH Range: 7.0 – 8.3
- Ideal pH: 7.2 – 8.0
- GH (General Hardness): 12–30 dGH
- KH: Moderate to high
They are hard water fish and require minerals like calcium and magnesium for proper growth, fin development, and reproduction.
If your water is soft:
- Add crushed coral to the filter
- Use mineral buffers
- Consider aragonite substrate
Water Quality Requirements
- 0 ppm Ammonia
- 0 ppm Nitrite
- Nitrates under 20–30 ppm
- Weekly 20–30% water changes
- Fully cycled tank required
Swordtails are active swimmers and produce moderate waste, so good filtration is important.
Tank Size & Setup
- Minimum Tank Size: 20 gallons (75 liters)
- Recommended for groups: 29+ gallons
They are energetic and need horizontal swimming space.
Tank Setup Tips:
- Open swimming area in the middle
- Plants along the sides and back
- Moderate water flow
- Secure lid (they can jump)
Floating plants help reduce stress and protect fry.
Feeding Frequency
- 1–2 times daily
- They are active feeders with fast metabolisms.
Feeding Quantity
- Only what they can consume in 2 minutes
- Remove uneaten food to prevent water pollution
Red Comet Swordtails require a balanced diet of plant matter and protein.
Staple Diet
- High-quality tropical flakes or pellets
Plant Matter (Very Important)
- Spirulina flakes
- Blanched zucchini
- Shelled peas
- Spinach
They require more plant material than many beginners realize.
Protein Treats (1–2x weekly)
- Frozen or live brine shrimp
- Daphnia
- Bloodworms (occasionally)
Protein enhances growth and intensifies their red coloration.
Tank Mates & Social Compatibility
Swordtails are peaceful but active and occasionally assertive.
Group Size
- Keep in groups of 4–6 minimum
- They are social and display better behavior in groups.
Male-to-Female Ratio
Males are persistent breeders and may chase females constantly.
✅ Good Tank Mates
- Platies
- Mollies
- Guppies
- Peaceful Tetras
- Corydoras Catfish
- Kuhli Loaches
- Peaceful Rasboras
Choose species that enjoy similar hard, alkaline water.
❌ Avoid
- Large Cichlids
- Oscars
- Aggressive fin nippers (Tiger Barbs in small tanks)
- Very slow, long-finned fish
Male Swordtails may spar with other males, especially in small tanks.
Physical Body Features
Color Pattern – “Red Comet”
- Bright red or orange-red body
- Contrasting white or lighter caudal (tail) area
- Black edging may appear on fins in some strains
The exact pattern varies by breeding line.
Signature Sword
- Only males develop the elongated lower extension of the tail fin.
- The “sword” can grow up to half the length of the body.
- Females do NOT have a sword.
Size
- Males: 3–4 inches (7–10 cm) plus sword
- Females: 4–5 inches (10–12 cm)
Females are larger and heavier-bodied.
Sexual Dimorphism
Males
- Slimmer body
- Gonopodium (pointed anal fin)
- Extended sword tail
Females
- Larger, rounder body
- Fan-shaped anal fin
- No sword
- Breeding & Fry Information
Swordtails are livebearers.
- Gestation: ~28 days
- Fry are born fully formed and free-swimming
- Females can store sperm and give birth multiple times
Provide dense plants (Java moss, floating plants) if you want fry survival.
Adults may eat babies if not separated.
Advanced Care Tips
- Provide strong filtration but avoid extreme current
- Maintain stable minerals for proper fin development
- Add vegetable matter regularly to prevent digestive issues
- Watch male aggression in small tanks
- Perform regular water changes due to their high activity level
