Expert advice from an experienced UK fishkeeper. Every guide is backed by cited sources, including peer-reviewed papers, FishBase, IUCN, SeriouslyFish and trusted expert videos, so the page helps customers choose with confidence before they buy.
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Best starting points
These guides help customers understand cycling, water testing and plant basics before they pick fish for the tank.
Choose the intended fish before the aquarium, place the tank on a suitable level support, install a filter and thermostatic heater, condition and test the water, then complete a fishless cycle. Add fish only after the chosen maturation process reaches its defined endpoint and repeated tests show zero ammonia and zero nitrite; elapsed days alone do not prove readiness.
There is no universal set of perfect freshwater aquarium parameters. Identify the animals, learn what the test and unit actually report, establish your local source-water baseline, and compare repeat measurements. In an established aquarium, a confirmed ammonia or nitrite detection needs investigation; pH, GH, KH, temperature and nitrate decisions depend on the species, life stage and whole system.
For a first low-tech planted aquarium, start with one or two correctly labelled lower-demand species, match their mature size to the tank, keep the rhizomes of Java fern and Anubias above the substrate, and change only one lighting or feeding variable at a time.
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The same advice as the guides below, filmed in our own fishroom — quick answers you can watch while the tank fills.
Expert Care, Cited Sources
Every guide is backed by FishBase, peer-reviewed papers, and real-world experience
11 guides
Peaceful shoals, livebearers and centrepiece fish for mixed tanks.
Start here: use a mature, filtered aquarium at least 60 cm long. FishBase and OATA compile groups of five or more; our conservative planning screen starts at eight, then checks usable volume, water, filtration and every adult tank mate.
Cardinal tetras are small, social blackwater fish, but they need more than a small volume of water. Our conservative starting policy is a mature, filtered aquarium at least 60 cm long and about 60 litres, a group of 10 or more, a routine target of 24-27 °C, and water chosen from measured supplier and home values rather than a fixed UK tap-water recipe.
Ember tetras are very small Brazilian social fish, with a maximum recorded length of 2.0 cm excluding the tail. Keep them only in a fully cycled, stable aquarium. We recommend a group of at least 10 and about 45 litres with a 45 × 30 cm footprint rather than using a litres-per-fish formula.
Our conservative starting policy is a mature, filtered aquarium at least 60 cm long and about 60 litres, eight or more fish, and measured water screened against 22-25 °C, pH 5-7 and 5-12 dGH.
Plan a mature, densely planted aquarium with at least a 45 × 30 cm base for a social group. Use 20–26°C, pH 6.5–7.5 and 5–15 dGH as published screening ranges, then hold a stable value inside the overlap for every animal in the tank.
Guppies are social livebearers suited to a prepared beginner, not a fish-per-litre formula. Use a mature filtered aquarium, tested neutral-to-alkaline mineral-bearing water, deliberate sex and population planning, open swimming room, cover and a separation option.
Endler's livebearer is a small, social, rapidly reproducing Venezuelan fish. Start with a mature filtered aquarium, a deliberate sex and population plan, stable tested medium-hard water, open swimming room and cover. Our conservative house screen is an aquarium at least 60 cm long and a group of five or more where capacity allows.
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.
Mollies are social livebearers sold under a broad trade name. Identify the species or domestic form first; plan at least 45 litres for a small group of smaller mollies or 80 litres for sailfins, then verify adult size, water, sex ratio and the complete community.
Start with a mature, filtered aquarium at least 60 cm long. Published size records disagree, and broad group guidance is not Honey-Gourami-specific, so verify Trichogaster chuna, the seller's adult-size advice and any claimed sexes before choosing one fish or a group.
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.
5 guides
Catfish, loaches and grazing species that need the right setup.
Identify the exact cory catfish before choosing care. Our starting policy for many common medium species is six compatible conspecifics, a mature 60 x 30 cm aquarium of about 60 litres, smooth fine sand and measured species-appropriate water.
Kuhli loaches are peaceful, slender Pangio loaches that need an established, escape-resistant aquarium with cover and a social group. As a conservative UK planning floor, use at least five compatible individuals and an aquarium of at least 80 litres for the smallest loaches; adult identity, dimensions, water, companions and filtration can require more.
Otocinclus are small South American loricariid catfish, not disposable algae cleaners. Confirm the supplied species where possible; start with a mature, stable aquarium with ample grazing surfaces; plan a compatible social group; and provide suitable food even when algae is visible.
For one typical common bristlenose, start with a mature, filtered aquarium of at least 90 litres, useful floor area, wood and cover. OATA reports about 15 cm adult length, 22-27°C, pH 6-8 and 4-12 dGH. Confirm the exact trade identity before applying species-level claims.
‘Pleco’ is a loose aquarium-trade label, not one species or one care sheet. Before buying, confirm the scientific name or defensible L-number, adult size and measurement method, required footprint, temperature and water, diet, social plan and source. No universal pleco tank size, menu or algae result is honest.
4 guides
Invertebrate guides for planted tanks and clean-up crews.
Choose an identified shrimp before copying care numbers. A mature, filtered 20-litre aquarium is our cautious starting policy for a small group from a source-documented Neocaridina davidi trade line—not a biological minimum or per-litre formula. Test your actual tap and tank water, protect the filter inlet, provide established grazing surfaces, and treat tank mates, medicines and breeding as species-specific decisions.
Use a mature, filtered aquarium and measured water—not a shrimp-per-litre rule. Tropical Fish Co uses 20 litres as a cautious starting policy for a small Cherry Shrimp group, above OATA's general 10-litre screen for small shrimp. Provide established grazing surfaces, cover and a protected filter inlet. No fish is guaranteed shrimplet-safe, and breeding should never be promised.
Start with a mature, filtered aquarium. OATA's broad UK guidance suggests approximately 20 litres for Amano Shrimp and at least five for social shrimp, with a larger aquarium when fish are present. Treat those as cautious planning screens—not biological minima or a per-litre formula. Match the complete adult community, test your water, protect the filter inlet and never buy them as a guaranteed algae cure.
Nerite snail is a trade umbrella, not one species. Confirm the supplied taxon and holding water, use a mature covered aquarium with established grazing surfaces, stock from food availability rather than a litre formula, and treat egg capsules, medicines and tank mates as species-specific decisions.
3 guides
Higher-care species where tank size and water stability matter.
Cichlids are a family of roughly 1,800 accepted species, not one care type. Before buying, identify the exact species and source, then compare adult measurement, usable tank dimensions, social system, territory, tested water, diet and an exit plan. No family-wide minimum tank, water range or tank-mate list is safe.
Freshwater angelfish are tall South American cichlids, not small community fish. OATA gives 120 litres as an industry floor for a compatible pair and says the aquarium must be sufficiently tall. We prefer planning around roughly 200 litres, a 100 × 40 cm footprint and about 50 cm height for an adult pair, with more space and an exit plan for a group.
Discus are social Amazonian cichlids with specialised aquarium needs. OATA advises at least five fish, except an established breeding pair, and about 50 litres per adult—roughly 300 litres for six adults. Use that as a planning floor, then check usable dimensions, filtration, source water and the actual fish.