Over Halfmoon RPG (OHM RPG)

Small, belligerent, and at home in hard alkaline water.

Meet the OHM RPG betta: a striking 7–8 cm aggressive show fish built for high-pH aquariums. Buy healthy OHM RPG livestock online with expert care support.

• Water conditions: The OHM RPG is best maintained in a stable pH range of 7.4–8.0, which suits its high-pH requirement without forcing rapid chemical swings. Keep temperature at 25–27.5°C, general hardness around 8–12 dGH and carbonate hardness around 4–8 dKH. Because ammonia is more toxic at higher pH, a fully cycled filter is essential: ammonia and nitrite must read zero, and nitrate should stay below 20 ppm. Test pH, KH and nitrogen compounds weekly, avoid pH-adjusting chemicals, and use drip acclimation over 45–60 minutes. A tight-fitting lid is important because this betta can jump.
• Tank setup and size: For a solo specimen, use a 30–40 litre aquarium with a wide footprint rather than a tall, narrow tank. If you plan a community setup, provide at least 60 litres and a 60 cm footprint so territory can be divided. Use a gentle filter with low flow, plenty of live or silk plants, floating cover, caves and broad leaves for resting. A dark background and subdued lighting help reduce stress. Avoid mirrors left in place, strong currents and bare tanks that offer no visual barriers.
• Temperament and aggression: The OHM RPG is an aggressive betta and should never be housed with another betta, male or female, except during carefully managed breeding. It may flare at reflections, snails or tank mates, so use mirrors for only brief exercise sessions. Aggression varies by individual: some specimens tolerate peaceful community fish, while others must remain solitary. Watch for chasing, fin nipping and guarding of the filter or cave area, and be ready to separate if bullying begins.
• Suitable tank mates: The safest approach is a species-only setup. In a spacious, well-planted high-pH community tank, robust peaceful fish such as platies, mollies and larger nerite or mystery snails may work, but success depends on the betta’s individual temperament. Avoid guppies, barbs, danios, cichlids, other bettas, fancy shrimp and any fin-nipping species. Introduce tank mates before the betta where possible, provide broken sight lines, and quarantine all livestock. Never add small fish or shrimp as “clean-up crew” without expecting predation.
• Feeding habits: The OHM RPG is carnivorous and thrives on a high-protein diet. Offer 2–3 betta-specific pellets twice daily, plus frozen or freeze-dried bloodworm, brine shrimp and daphnia two or three times weekly. Soak freeze-dried foods briefly to reduce digestive risk, and remove uneaten food after a few minutes. A fasting day once weekly helps prevent bloating. Overfeeding is a common cause of constipation and water-quality problems, so feed small portions and adjust according to body condition rather than appetite alone.
• Routine care and maintenance: Perform a 25–30% water change weekly with temperature-matched, dechlorinated water, and vacuum the substrate to remove waste. Rinse filter media only in tank water to protect beneficial bacteria. Keep the tank covered, maintain stable temperature and avoid moving decor frequently. Observe fins, appetite and swimming behaviour daily; early signs of clamping, white edges or lethargy warrant immediate water testing and isolation if needed. Quarantine new livestock and never share equipment between tanks without disinfection.
• High-pH health considerations: Stable high pH is easier on this fish than a fluctuating pH, so prioritise consistency over chasing a specific number. High pH makes ammonia more dangerous, meaning filtration and stocking levels must be conservative. Avoid overstocking, decaying food and clogged filters. If pH must be adjusted, do so gradually and preferably by matching source water rather than using temporary buffers. Keep a test kit for ammonia, nitrite, nitrate and pH, and act quickly if any ammonia or nitrite is detected.
• Acclimation and introduction: Float the bag for 15–20 minutes to equalise temperature, then drip-acclimate over 45–60 minutes, especially when moving between different pH levels. Turn off aquarium lights during introduction to reduce stress. Release the fish gently with a net rather than pouring bag water into the tank. Observe closely for the first 48 hours for hiding, gasping, flaring or aggression. Provide a quiet settling period and resist adding tank mates immediately; stability and clean water are the best start for an aggressive, high-pH OHM RPG betta.