Halfmoon Betta (Rosetail Blue rim)

Rosetail Blue Rim: an aggressive, high-pH beauty reaching 6–7cm. Its vivid blue-rimmed rosetail makes it a showpiece for expert aquarists with alkaline setups.

• Water Conditions (High pH & Alkaline Stability): The Rosetail Blue Rim hails from mineral-rich, rift-lake environments where the water is distinctly alkaline and stable. You will need to maintain a pH level consistently between 7.8 and 8.6, along with a general hardness (GH) of 10–20 dGH and carbonate hardness (KH) of 8–12 dKH. These parameters must remain rock-solid; sudden drops in pH can cause severe stress, loss of colour, and a compromised immune system. Keep the temperature steady in the range of 24–28°C (75–82°F), using a reliable submersible heater with a thermostat and a separate thermometer for accuracy. Because this species produces a notable bioload, robust filtration is non-negotiable. We recommend a canister filter or a high-capacity hang-on-back filter that turns over the tank volume at least 6–8 times per hour. Weekly partial water changes of 25–30% are essential to dilute nitrates and replenish buffering capacity. To maintain that high pH, use crushed coral, aragonite sand, or inert limestone as the substrate; these natural buffers slowly dissolve and help keep alkalinity high between water changes. If municipal tap water is soft or acidic, you will need to remineralise with a dedicated alkaline buffer product. Regular testing (at least twice weekly) with a liquid API test kit ensures no drift in parameters. Avoid driftwood, peat moss, or almond leaves in the tank, as these leach tannic acids that will rapidly drop pH and harm the fish.
• Aggressive Temperament & Tank Mates: The Rosetail Blue Rim is firmly in the "aggressive" category, and this is not a fish to be underestimated. It demonstrates strong territorial behaviour, particularly during feeding and when it has claimed a rocky cave or spawning site. It will chase, nip fins, and occasionally engage in physical conflict with tankmates. For this reason, it is not a community fish in the conventional sense. Best kept in a single-species setup or alongside other robust, similarly-sized aggressive