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Betta splendens

Betta spl. female Halfmoon Blue - Betta Fish for Sale UK

Moderate Care
Semi-Aggressive
£14.99Sold Out

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Live arrival guaranteed. If they don’t arrive healthy, email us a short unboxing video the same day for a replacement or refund. Packed in oxygenated bags with insulation and heat packs when needed.
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A striking blue female Halfmoon betta with flowing fins and bold personality, ideal for a warm, peaceful, well-maintained aquarium. Moderate care, semi-aggressive. 24-30C, pH 6.0-7.5.

Care at a Glance

Scientific Name
Betta splendens
Max Adult Size
6–7 cm
Lifespan
3 years
Care Level
Moderate
Temperament
Semi-aggressive
Temperature
24–30°C
pH Range
6–7.5
Hardness
1–15 dGH
Minimum Tank
at least 20 litres, preferably 25+
Diet
Carnivore

Adult size is the maximum length this species reaches at full maturity (scientific sources). The livestock you receive will be younger and smaller. Product-photo provenance and any image-specific limitations are stated on the listing.

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Blue and red male Betta splendens swimming side-on in an aquarium
Full Care Guide

Betta Fish Care Guide: Siamese Fighting Fish

For one typical domestic Betta splendens, start with at least 20 litres, a mature filter, thermostatic heater, separate thermometer, gentle flow, a secure lid with surface access, and plants or refuges. Keep one male per aquarium.

13 min readRead guide

Water Parameters

Maintain these water conditions for optimal health and vibrant colors

Temperature
24–30°C
24°CIdeal30°C
pH Level
6–7.5
6Ideal7.5
Water Hardness
1–15 dGH
1 dGHIdeal15 dGH

Blue Halfmoon females run larger than many keepers expect — this line is recorded at 6 to 7 cm, putting her on par with plenty of males for sheer presence. She wears the classic deep blue across body and broad halfmoon-type tail, and displays it freely: females flare too, just with less finnage and more economy of motion.

Her file leans firmly toward solo housing. Best kept alone is the headline guidance; if tank mates are attempted at all, they should be very peaceful, non-nippy species in a larger, heavily planted aquarium, with small snails acceptable and shrimp at genuine risk of being eaten — smaller species especially. Excluded outright: other bettas, fin-nipping fish such as tiger barbs, aggressive or highly territorial species, large predators, and brightly coloured long-finned fish that trigger displays. Space her at a minimum of 20 litres, preferably 25 or more, with water between 24 and 30 °C, pH 6.0–7.5 and hardness 1–15 dGH. Moderate care covers the rest: steady heat, clean water, carnivore feeding, and a tolerance for the occasional territorial mood, particularly toward breeding condition. She lives high in the water column.

Respect her preference for solitude and she is among the easiest large females to keep well. One fish in 25 litres means chemistry stays docile, feeding is a ten-second task, and the weekly change inside pH 6.0–7.5 and 1–15 dGH takes minutes. Her size — up to 7 cm — earns her slightly larger carnivore portions than smaller females, and her wide 24–30 °C tolerance forgives imperfect heater placement. Aquascape for the top third of the tank where she actually lives: floating cover, open surface for feeding, structure she can patrol past. The deep blue holds best under consistent conditions, and consistency is the entire skill this fish asks you to have.

Blue Halfmoon female parameters

  • Size range 6–7 cm
  • Lifespan ~3 years
  • Moderate care commitment
  • Semi-aggressive — prefers solitude
  • 24–30 °C
  • pH 6.0–7.5
  • 1–15 dGH
  • 20 litres minimum, 25+ preferred
  • Carnivore
  • Top-region swimmer

One thing before you order

Plan her as a single-specimen showpiece and you cannot go wrong; she carries an entire aquarium on her own. UK shipping via licensed live-animal courier, protected by our live arrival guarantee.

Customer Reviews

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What customers say about ordering from us

  • 4 out of 5Verified buyer

    I have a small group of long finned mountain minnows. So was delighted to be able to order ten of this variety to increase the genetics in my tank . The ones I recieved are healthy but it’s to early to give a verdict on wether they are of a long finned type since they are small currently.

    Gordon Walker · 23 Sept 2026

  • 5 out of 5Verified buyer

    100% success travel and "installation". Pleased with quality of purchase. The Siamese fighter a bit "shy" so have not yet seen him at his best yet but looking good. Happy customer. GG

    George E Garratt · 21 Sept 2026

Reviews of our shop, collected by Judge.me, an independent third-party review collector. Newest first.