Reasons:
- Temperament: Male bettas are known for their territorial and aggressive behavior, especially toward other fish with similar appearances or long fins. Black ghost knife fish are generally peaceful but may become aggressive if their territory is threatened. Keeping them together can lead to constant conflicts and stress for both fish.
- Size difference: Black ghost knife fish can grow up to 12 inches (30 cm) in length, while male bettas typically reach a maximum size of 2-3 inches (5-7.5 cm).
This significant size difference can create an imbalance in the tank's ecosystem, with the larger black ghost knife fish potentially preying on the smaller betta.
- Water requirements: Male bettas prefer warm water temperatures between 76-82°F (24-28°C), while black ghost knife fish thrive in cooler water temperatures around 72-78°F (22-26°C).
Trying to maintain a temperature range suitable for both species can be challenging and may compromise the health of one or both fish.
- Tank size: Black ghost knife fish require a spacious aquarium with plenty of swimming space and hiding spots, typically a minimum tank size of 50 gallons (189 liters) or more. Male bettas, on the other hand, can be kept in smaller tanks, such as 5-10 gallons (19-38 liters).
Keeping them together in a tank that's too small for the black ghost knife fish can result in overcrowding and increased stress levels.
- Nocturnal behavior: Black ghost knife fish are nocturnal, meaning they are most active at night.
Male bettas are primarily diurnal (active during the day), so their activity patterns may clash, potentially leading to further conflicts and stress.
Overall, housing a male betta with a black ghost knife fish is not recommended due to differences in temperament, size, water requirements, preferred tank sizes, and activity patterns. It's better to keep these species separately to ensure their well-being and prevent potential problems.