Neon Tetra and Harlequin Rasbora — The Classic Pair
Neon tetras (Paracheirodon innesi) remain the world's most sold aquarium fish for good reason. They are visually striking, peaceful, hardy within their preferred parameters, and available at every fish shop in Cambodia for under 2,000 KHR each. The iconic blue-and-red stripe is brightest in soft, slightly acidic water (pH 6.0-7.0, TDS under 150 ppm), so if your tap water is very hard, consider blending with RO water for the best colour display. Keep a minimum school of 8; below this the school fractures and individual fish become stressed. Tank size minimum is 40L, ideal is 60L.
Harlequin rasboras (Trigonostigma heteromorpha) are the neon tetra's more forgiving cousin. They tolerate harder water better (up to pH 7.5), are slightly larger at 4-4.5 cm, and display a beautiful black triangular patch on a copper-orange body. They are equally peaceful and make excellent tankmates for neons, corydoras, and dwarf gouramis. Harlequins are slightly more active than neons and tend to swim higher in the water column, creating a natural layering effect when kept together. Available widely in Phnom Penh markets year-round.
Both species are ideal first schooling fish. If choosing between them for a first tank in Cambodia, harlequin rasboras edge ahead for pure beginners because of their greater tolerance for municipal tap water. Neons reward a beginner who invests in a basic RO or conditioning system with dramatically more vibrant colour and longer lifespan — up to 5 years versus 2-3 years in suboptimal water.
- ✦Buy neon tetras and harlequins in groups of 10+ — the price per fish drops significantly and the school looks far more impressive
- ✦Neon tetras ship stressed — quarantine for 2 weeks and feed live baby brine shrimp to restore colour before adding to the display tank
- ✦In Cambodia's hard tap water, add 1 teaspoon of peat extract per 10L to soften and acidify water for neon tetras without buying RO equipment
Platy and Molly — Unbeatable for Beginners
Platies (Xiphophorus maculatus) are arguably the single best beginner fish available. They tolerate water conditions from pH 7.0-8.2, temperature 20-28°C, and TDS up to 400 ppm — meaning they thrive in virtually any Cambodian tap water. They are livebearers that give birth to fully formed fry, are peaceful with all non-aggressive species, and come in dozens of colour forms from sunset to tuxedo to red wagtail. A single platy in a community tank will live 3-5 years with basic care. They are available at nearly every fish market in Cambodia for under 3,000 KHR.
Mollies (Poecilia sphenops and hybrids) share the platy's toughness but have one important difference: they genuinely benefit from slightly brackish water. Adding 1-2 teaspoons of aquarium salt per 10 litres improves their health significantly, reduces disease susceptibility, and extends lifespan. In Cambodia's warm climate, black mollies and dalmatian mollies are both widely available and bred locally. They are slightly larger than platies at 6-8 cm for females, so they need at least 60L. Keep 2 females per male to prevent harassment.
Both platies and mollies reproduce prolifically. In a community tank, most fry will be eaten by other fish, maintaining a natural balance. If you want to raise fry, provide dense floating plants like java moss or hornwort as cover. One beginner mistake is keeping too many males — male platies and mollies chase females relentlessly, causing stress and early death. A 1:2 or 1:3 male-to-female ratio is ideal in all livebearing setups.
- ✦Add 1 teaspoon of non-iodised salt per 10L for mollies — this prevents white spot disease which is common in Cambodia's rainy season
- ✦Keep platies at a 1:3 male-to-female ratio to prevent the constant chasing that shortens female lifespan
- ✦Platies and mollies will hybridise if kept together — keep species separate if you intend to breed either for sale
Corydoras and Otocinclus — The Essential Bottom Crew
Corydoras catfish are indispensable in any community setup. They process substrate food scraps, are completely peaceful, and their armoured bodies make them immune to the fin-nipping that plagues other bottom dwellers. False julii corydoras and sterbai corydoras are the most commonly available species in Cambodia, both thriving at 25-28°C. They must be kept in groups of at least 6 — solo corydoras display stress behaviours and refuse to forage actively. A fine sand substrate is strongly preferred over gravel, as their sensitive barbels (whiskers) are easily damaged by sharp gravel.
Otocinclus catfish (Otocinclus affinis) are the algae-cleaning specialists of the community tank world. At 3-4 cm they are small enough for 30L tanks and completely ignore all tankmates. They rasp green soft algae from glass and plant leaves without damaging the plants — unlike bristlenose plecos which occasionally tear leaves. Otocinclus are more delicate than corydoras and sensitive to copper-based medications, ammonia spikes, and being the first fish in a new tank. Establish the tank for 4-6 weeks and grow some algae before adding them.
Together, corydoras and otocinclus form the perfect bottom maintenance pair. In a 60L community tank, 6 corydoras and 4-5 otocinclus handle substrate and glass cleaning respectively, reducing manual cleaning significantly. Both species are available in Phnom Penh fish markets, though otocinclus are less common than corydoras and may require ordering from specialist suppliers. Feed corydoras sinking wafers at night when lights go out — they are primarily nocturnal feeders.
- ✦Use fine pool filter sand for corydoras — it costs under $5 per 5 kg at Phnom Penh hardware stores and is far healthier than gravel for their barbels
- ✦Never use copper-based medications in a tank with otocinclus — even trace amounts are lethal to these catfish
- ✦Feed corydoras sinking algae wafers after lights out — in bright community tanks they often wait until dark to forage
Cherry Barb, Zebra Danio, and Honey Gourami
Cherry barbs (Puntius titteya) are one of the few barb species completely safe in a community tank. Unlike tiger barbs which fin-nip relentlessly, cherry barbs are gentle, slow-moving, and peaceful with all tankmates. Males display a vivid cherry-red colour when in breeding condition, especially against a dark background. They need a minimum school of 6, prefer planted tanks with some shade, and do best in soft to medium-hard water. Cambodia's Phnom Penh markets occasionally stock them — if unavailable locally, they are worth ordering from Bangkok suppliers.
Zebra danios (Danio rerio) are the benchmark for beginner hardiness. They survive temperature fluctuations from 18-28°C, tolerate a wide pH range, and recover from poor water quality that would kill more sensitive fish. They are energetic schoolers that add constant top-to-mid movement in any tank. The longfin variant has flowing fins that add elegance without the care difficulty of bettas. One caution: zebra danios are fin nippers when underfed or understocked — keep groups of 8+ and feed twice daily to suppress this behaviour.
Honey gouramis (Trichogaster chuna) are the gentlest gourami species and one of the best centerpiece fish for 40-80L community tanks. Males display a stunning honey-yellow and orange colouration that intensifies when courting. Unlike dwarf gouramis (which carry iridovirus disease risks), honey gouramis are generally disease-resistant and long-lived. They are labyrinth fish that breathe air, so ensure the water surface is not fully covered. Keep one male with one or two females in a peaceful community — two males in a small tank will fight.
- ✦Cherry barbs colour up most intensely against a dark substrate — use black sand to make males look their best
- ✦Zebra danios will jump — any tank housing them needs a tight-fitting lid, especially important in Cambodia's open-top style tanks
- ✦Honey gouramis are shy when first introduced — add floating plants and reduce flow to help them settle within the first week
Endler Guppy, Kuhli Loach, and Bristlenose Pleco
Endler guppies (Poecilia wingei) are the nano fish world's hidden gem. Males reach only 2-3 cm and display wildly varied colour patterns — metallic greens, orange spots, and black markings that rival any fish twice their size. They breed freely but produce far fewer fry than regular guppies, making population control easier in community tanks. Endlers tolerate hard water well and thrive at Cambodia's ambient temperatures. They are peaceful with all non-aggressive fish and can be kept with dwarf shrimp without predation risk — unusual for livebearers.
Kuhli loaches (Pangio kuhlii) are eel-shaped bottom dwellers that bring unique character to any community tank. They spend daylight hours hiding in tight spaces — under driftwood, inside pipes, in dense plant roots — and emerge at night to forage. They are completely peaceful and occasionally form tight groups with their own kind. Keep a minimum of 4-6; solo kuhli loaches hide permanently and are rarely seen. They do best in soft, warm water with a fine sand substrate and plenty of hiding spots. Widely available in Cambodia at most fish markets.
Bristlenose plecos (Ancistrus sp.) are the ideal algae controller for 60L+ community tanks. Unlike common plecos that reach 45 cm, bristlenose stay at 10-13 cm and do not outgrow standard aquariums. They rasp algae from glass and hard surfaces, produce moderate waste, and are peaceful with all fish. Males develop distinctive fleshy tentacles on the snout that give them a prehistoric appearance. They need driftwood in the tank — they rasp cellulose from wood as a dietary supplement, and without it can develop digestive problems. Feed algae wafers nightly as a supplement to natural algae grazing.
- ✦Endler guppies are ideal for Cambodia's nano tank market — a 20L planted Endler tank is a complete low-cost ecosystem
- ✦Kuhli loaches need tubes or caves specifically sized for them — a 3 cm diameter PVC pipe section cut to 10 cm provides a perfect hide
- ✦Add a piece of driftwood specifically for bristlenose plecos — it is not optional decoration, it is a nutritional necessity for their digestive health