Easy
Swordtail Black (Xiphophorus helleri black)
22–27°C · pH 7–8 · 108L
£3.99
Montezumae Swordtail — petite 4 cm Mexican line for hard, alkaline water. Peaceful, easy care, suitable for tanks from just 60 litres.
Care at a Glance
Scientific Name
Xiphophorus helleri
Max Adult Size
up to 4 cm
Lifespan
3 years
Care Level
Easy
Temperament
Peaceful
Temperature
23–27°C
pH Range
7–8.5
Hardness
5–30 dGH
Minimum Tank
60L
Diet
Omnivore
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.
Water Parameters
Temperature
23–27°C
23°CIdeal27°C
pH Level
7–8.5
7Ideal8.5
Water Hardness
5–30 dGH
5 dGHIdeal30 dGH
Xiphophorus helleri
Swordtail Montezumae (Xiphophorus helleri montezumae) - Tropical Fish for Sale UK
Beginner Friendly
Peaceful
£3.99/ fishSold Out
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— save up to 30%Shoaling fish: kept in a group they feel safer, stay calmer and show their best colour.
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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.
£19.95 tracked delivery — half price (£9.98) from £100.00, free from £200.00. One delivery charge however many fish you add — everything travels together with a licensed live-animal courier.
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Montezumae Swordtail — petite 4 cm Mexican line for hard, alkaline water. Peaceful, easy care, suitable for tanks from just 60 litres.
Care at a Glance
Scientific Name
Xiphophorus helleri
Max Adult Size
up to 4 cm
Lifespan
3 years
Care Level
Easy
Temperament
Peaceful
Temperature
23–27°C
pH Range
7–8.5
Hardness
5–30 dGH
Minimum Tank
60L
Diet
Omnivore
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.
Full Care Guide
Platy Fish Care: Tank Size, Temperature & Types
Platy is a trade name used for Xiphophorus maculatus, X. variatus and domestic forms. Start with at least three in a mature aquarium of at least 45 litres, verify the exact fish and measured water, and plan extra capacity before mixing sexes.
16 min readRead guide
Water Parameters
Maintain these water conditions for optimal health and vibrant colors
Temperature
23–27°C
23°CIdeal27°C
pH Level
7–8.5
7Ideal8.5
Water Hardness
5–30 dGH
5 dGHIdeal30 dGH
Hard, alkaline water is where this Mexican line feels most at home, which makes the Montezumae Swordtail (Xiphophorus helleri montezumae) a thoroughly practical choice for keepers whose water leans that way. If your kettle furs up quickly, your supply is probably exactly what this fish enjoys. It is petite — listed at 4 cm — and with a listed minimum tank of just 60 litres it opens swordtail keeping to more modest aquariums than the family usually demands. Most swordtails ask for three-figure tank volumes; this line's 60-litre listing is the exception that makes it worth a second look.
True to its relatives, it is peaceful and easy to care for. Suitable companions include other peaceful livebearers, platies, mollies, guppies, peaceful tetras and Corydoras catfish; large aggressive cichlids, fin-nipping barbs, aggressive or highly territorial species, large predators and very delicate slow-moving fish are the ones to refuse. The companion options span a small community comfortably, so even a compact aquarium can feel fully stocked without breaking the peace.
Water parameters mirror its hard-water leanings: pH 7.0–8.5, hardness from 5 to 30 dGH and a temperature of 23–27 °C. Despite the smaller tank allowance, the usual rules still apply — stable temperature, clean filtered water and a varied menu for an omnivorous feeder. It swims at the middle level and typically lives about three years.
Montezumae care summary
- Petite: listed at 4 cm
- Tanks from 60 litres
- 23–27 °C water
- pH 7.0–8.5; hardness band 5–30 dGH
- Omnivorous diet; easy care
- Peaceful; midwater; lifespan around 3 years
Buying notes for UK keepers
Sixty litres is an achievable footprint for most homes, making this a swordtail you can plan around rather than upsize for. For a desk-side or bedroom aquarium, few swordtails fit the brief as neatly. Combine it with gentle community species and hard-water-tolerant planting for a coherent set-up. Acclimatise with patience and it settles into the middle of the tank, exactly where the care sheet says it lives. Your order is handled by a licensed live-animal courier and protected by our live arrival guarantee.
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What customers say about ordering from us
4.6 on Google Maps, rated 4.6 out of 5 (opens in a new tab)4.4 · 91 shop reviews read them, rated 4.4 out of 5
- 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
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