Over halfmoon (OHM Blue)

Seven centimetres of blue aggression, built for hard, alkaline water.

Meet the OHM Blue betta: a striking over-half-moon tail, rich blue colour and confident, aggressive nature. Tolerant of higher pH and perfect for a species-only setup.

• Water conditions: The OHM Blue is a Betta splendens variety that adapts well to stable, higher-pH water. Aim for pH 7.0–8.0, with 7.2–7.8 being a practical target for most keepers; if your tap water sits above 8.0, acclimatise slowly and avoid sudden swings. Temperature should be 24–28°C (75–82°F), maintained with a reliable heater and thermometer. General hardness can range from soft to moderately hard, but consistency matters more than a specific reading. Keep ammonia and nitrite at zero, nitrate below 20 ppm, and run a fully cycled filter with gentle flow — over-half-moon fins are heavy and dislike strong current. A tight-fitting lid is essential because bettas are accomplished jumpers. Test water weekly and perform regular partial changes to keep parameters stable; high-pH water holds less ammonia in the safer ammonium form at lower pH, so vigilance with waste and feeding is important.
• Suitable tank mates: Because this betta has an aggressive temperament, the safest and most responsible setup is a species-only aquarium. Males should never be housed together, and male/female pairs should only be combined for controlled breeding. Avoid small, colourful or long-finned fish such as guppies, neon tetras, barbs, danios and other bettas, as they may be chased, nipped or injured. In a very large, well-planted tank (90 cm/36 inches or more), some keepers report success with robust, fast-moving dither fish that are too large to be eaten and not fin-nippers, but this always carries risk and depends on the individual fish. Nerite snails may be tolerated in some setups, while shrimp are likely to be treated as prey. If you want a peaceful community, choose a different centrepiece fish; the OHM Blue is best appreciated on its own.
• Feeding habits: The OHM Blue is an obligate carnivore that thrives on a varied, protein-rich diet. Offer high-quality betta pellets as the staple, feeding only what the fish can eat in 1–2 minutes — typically 2–3 pellets twice daily, adjusted for the fish’s size and activity. Supplement with frozen or live foods such as bloodworm, brine shrimp, daphnia, mosquito larvae and Mysis shrimp two or three times a week to support condition, colour and fin growth. Avoid overfeeding, which quickly fouls water and can lead to bloating or swim-bladder problems. A single weekly fasting day is useful for digestion. Soak freeze-dried foods before feeding to reduce the risk of constipation, and remove uneaten food promptly. Because this fish reaches 7–8 cm, it has a respectable appetite; monitor body shape and reduce portions if the belly becomes noticeably rounded.
• Care requirements: Provide a minimum of 20 litres (5 gallons) for a single OHM Blue, though 40 litres (10 gallons) or more is strongly preferred for stable water chemistry and swimming space. Use a gentle filter, a heater, a lid and plenty of cover — live plants, floating vegetation, botanicals and smooth caves — while avoiding sharp decor that can tear the heavy over-half-moon fins. Keep lighting moderate and provide shaded areas so the fish can retreat. Perform 25% water changes weekly, gravel-vacuum regularly and rinse filter media only in tank water. Because high-pH water can make some medications and ammonia more problematic, quarantine new additions and act quickly at the first sign of clamped fins, white spots, fin rot or lethargy. Monitor fin condition daily; over-half-moon tails are prone to curling and damage, so keep flow low and avoid overcrowding. This is a intelligent, interactive fish that benefits from enrichment such as a mirror for short sessions and occasional live-food challenges. With stable parameters, warm water and good nutrition, the OHM Blue can live for several years and remain a vivid, engaging centrepiece.