The real value is welcoming and caring for living things within what you can keep responsibly to the end — routing cashback for supplies and consumables is just a bonus on top

Why you need to set up the tank, filtration and water before welcoming any fish

When you decide to keep goldfish, tropical fish or killifish, it's tempting to picture a tank full of swimming fish right away. But in aquarium-keeping, the absolute priority is building the water before you bring home any fish. Tap water used directly will damage fish gills through chlorine; in a newly set-up tank where filter bacteria haven't yet colonised, ammonia and nitrite spike rapidly and kill the fish. After setting up the tank, wait at least one to two weeks for the beneficial bacteria to establish before adding any fish — this "cycling" process is the first and biggest hurdle in keeping goldfish and tropical fish.

There's also a question to ask yourself before you start: can you commit to caring for these animals for their full lifespan? Goldfish can live more than ten years in the right conditions. Tropical fish, depending on species, may live anywhere from a few years to nearly a decade. Rather than impulse-buying because something looks cute, or buying in bulk alongside a cashback deal, welcome only as many animals as you can genuinely care for within the limits of your tank size, management ability and daily routine. That commitment is the non-negotiable starting point. This article covers what is specific to goldfish, tropical fish and aquarium-keeping: the real cost of initial equipment, water-quality basics, the differences between goldfish and tropical fish, how to source livestock and the risks of DOA (dead on arrival) in online orders, and how to combine supply purchases with point-site cashback. For an equipment overview see the houseplant & aquarium guide. For pet supplies in general see the pet supplies & services guide, for pet food the pet food guide, and for general pet care products the general pet guide.

The real cost of getting started: equipment needs and set-up costs by tank size

If you assume "just buy a tank and you're done," the extra spending that follows will come as a surprise. Here is a breakdown of the minimum equipment you need and a rough guide to initial costs by size. Prices vary by retailer and season — treat these as reference figures.

Small starter kits (under 30 cm) are compact, but limited water volume makes water quality unstable, and overstocking makes the tank crash quickly. 45–60 cm tanks have enough volume to stay stable and are much easier to maintain long-term. "Smaller is easier" is a myth — in aquarium-keeping, more water volume is actually easier to manage. If you have the space, a 45–60 cm tank is worth considering from the start.

Something easily overlooked in tank preparation is the tank stand (dedicated stand) and the load capacity of the placement spot. A water-filled tank is heavier than you'd imagine, and even a standard size, combining water, substrate, and equipment, becomes quite heavy. Placing it on ordinary furniture or a storage shelf can't bear it and is dangerous, so prepare a dedicated stand suited to the tank size, and confirm the load capacity of the floor where you set it. Also, substrate, gravel, and the like are heavy and rack up shipping, so a home-center's official mail-order or in-store pickup is also a comparison candidate. Home centers are often strong in selection and price for tank stands and heavy gardening materials, so using different sources by purpose is rational (home-center guide). Redoing the setup means moving the tank with its contents, which is a hassle, so firmly deciding the placement spot first is the iron rule.

Water quality is the foundation of keeping: pH, hardness and the nitrogen cycle

Most fish deaths in aquariums are caused by sudden temperature changes or water-quality deterioration. "Cycling a tank" means establishing a colony of beneficial bacteria so that the biological filtration cycle works. In an uncycled tank, ammonia from fish waste is not broken down, converting instead into highly toxic nitrite, which kills the fish. Adding fish during this cycling period causes what is often called "new tank syndrome."

• Understand the ammonia → nitrite → nitrate cycle: Fish waste → ammonia (highly toxic) → bacteria convert it to nitrite (highly toxic) → further broken down to nitrate (relatively low toxicity). Nitrate is removed through regular water changes — that is the core routine.
• pH management: goldfish and tropical fish have different ideal ranges: Goldfish do best around pH 7.0–7.5 (neutral to slightly alkaline). Most tropical fish such as neon tetras prefer pH 6.5–7.0 (slightly acidic). Aqua soil tends to lower pH toward slightly acidic and suits tropical fish; coarse gravel stays more neutral to slightly alkaline and suits goldfish.
• Water-change frequency and volume: A general guideline is one to two times per week, replacing 20–30% of the total volume. Large water changes at once can flush out bacteria or cause sudden swings in temperature and chemistry. Small, regular changes are the standard.
• Temperature management: Most tropical fish prefer 24–28 °C depending on species. Sudden temperature swings trigger diseases like white spot (ich). Goldfish are cold-tolerant — generally 5–30 °C — but are also sensitive to sudden changes.
• Hardness (GH and KH): Tap water hardness varies greatly by region. RO water or a softening filter may be needed in some areas; start by testing your own tap water with a test kit.

A water-test kit and a digital thermometer are essentials from day one. Most cases of "I don't know why the fish died" turn out to involve no water testing at all. Building the habit of measuring what you cannot see is the key to long-term success.

Goldfish vs. tropical fish: the key differences in care

Even though both involve "keeping fish in a tank," goldfish and tropical fish require quite different approaches. Which is right for you depends on your lifestyle and the environment where you'll place the tank.

Goldfish produce a large amount of waste. Keeping too many in a small tank causes rapid water-quality deterioration. The common image of "keeping a fairground goldfish in a small bowl" is actually a harsh environment for the fish. As a rough guide, each goldfish needs about 10–20 litres of water, and a high-capacity external or top-mounted filter is recommended. In contrast, tropical fish offer impressive variety. A community tank combining peaceful small species such as neon tetras and corydoras catfish can create a beautiful aquascape even in a 45–60 cm tank. However, predation relationships (larger fish eating smaller ones) and differing water-quality needs must be considered carefully.

Community compatibility varies enormously by species. To avoid the scenario of "one fish was eaten by morning," always check compatibility with a specialist shop or reliable source before buying. Even within "tropical fish," some cichlids are highly aggressive and cannot be housed with other species.

In choosing goldfish or tropical fish, something easily overlooked on the running-cost side is the heater's electricity cost. Tropical fish basically need a heater to keep the water temperature year-round, and electricity use grows especially in winter. On the other hand, goldfish can often be kept without a heater, making electricity cost easier to curb in that respect. This difference accumulates the longer you keep them, so choosing by including not just initial costs but monthly running costs lets you keep it up comfortably. To curb electricity cost, keeping the water temperature with insulation and choosing an appropriately wattage heater are effective. Reviewing your home's electricity plan itself can also lower total fixed costs including the tank's maintenance cost (electricity & gas guide). Choose the one that fits your life by including not just "ease of keeping" but "ease of continuing (cost)" too.

Sourcing livestock: DOA risks in online orders and how to choose a specialist shop

Livestock (fish, shrimp, aquatic plants) can be sourced either from physical stores (specialist shops or home centres) or online. Each has its own advantages and risks.

• Advantages of physical stores (specialists): You can inspect the livestock's condition before buying; you can ask care questions; specialist shops that quarantine stock carry lower disease-introduction risk; they often have experience with local water conditions.
• Advantages and risks of online shopping: Access to rare species or varieties unavailable locally; easy price comparison. However, DOA risk (dead on arrival) is real. Summer heat and winter cold present the highest danger — temperature swings during shipping can be fatal. Compensation policies (whether DOA cover exists, the percentage covered, the claim process) vary significantly between shops.
• Reducing DOA risk: Ensure someone is home on the delivery day (absence is unacceptable). In summer and winter, consider requesting cold/warm packs or next-day morning delivery. Inspect the condition immediately on arrival; if DOA occurs, photograph and contact the shop within their claim deadline. Check reviews and reputation in advance; buy livestock only from specialist retailers with a proven track record in live shipping.
• Don't choose livestock based on cashback or deals: Even when a point site or discount coupon is available, select a livestock source based on "livestock condition, shop reliability and DOA compensation terms." A cheap shop with poor husbandry may send weak individuals or introduce disease.
• Treating aquatic plants: Plants in shop tanks may have been treated with pesticides. Shrimp (such as crystal shrimp) are extremely sensitive to pesticides — confirm the plants are pesticide-free, or soak them in water for several days to off-gas any residues before introducing them to the tank.

Tropical-fish specialist shops can be limited in some areas. As a risk-management approach, buy your first fish or plant from a physical shop where you can check their condition, then supplement with online orders for rarer varieties.

Something to think a bit further ahead about when taking in live creatures is moving the creatures and tank when relocating. A water-filled tank can't be carried as-is, creatures need water-temperature, oxygen, and stress management during the move, and a long-distance, long-duration move puts a big burden on them. Some moving companies refuse to transport creatures or tanks, so if there's a chance of relocating, starting at a comfortable scale with foresight into "how would I move this tank and these creatures if I moved" is reassuring (for moving logistics, see the moving guide). When moving, consideration to reduce the creatures' burden — dedicated transport bags, heat/cold preparation, water acclimation after the move — is essential. Since you're entrusted with lives, thinking ahead to "what to do when moving or in an emergency, before increasing them" is the responsible way to keep them.

Supplies, consumables and point-site cashback in practice

Unlike livestock, online purchases of aquarium supplies and consumables pair well with point-site cashback. Initial equipment such as tanks, filters, heaters and lights carries high unit costs, so routing a bulk purchase through a point site produces a meaningful cashback amount. Consumables such as food, dechlorinator, filter media, activated carbon and bacterial supplements are used regularly, creating repeated purchasing opportunities.

1. ① Determine your keeping environment and limits firstDecide on tank size, placement, management ability and daily routine to set the right equipment and stocking level. Welcome only as many fish as you can responsibly keep for their full lifespan.
2. ② Route initial equipment purchases as a batchBefore buying high-value items like a tank set, filter, heater and light online, check shop offers and cashback rates on Pointnavi and route through the point site. Buying together maximises the cashback amount.
3. ③ Buy consumables on a schedule that matches your usage ratePlan purchases of dechlorinator, filter media, food and bacterial supplements to match your actual usage. For heavy items (substrate, water treatment products), calculate your order to clear the free-shipping threshold. See the pet food guide for related tips.
4. ④ Prioritise specialist shops for livestock; use online as a supplementWhen sourcing livestock, prioritise shop reliability, the ability to check condition and DOA compensation over cashback rates. If ordering livestock online, ensure someone is home for delivery and confirm the compensation policy in advance.
5. ⑤ Pay with a cashback-earning payment methodUse your main economic zone's eligible payment method for supplies and consumables to stack additional cashback. Initial equipment orders are large, so the payment cashback impact is significant. See the economic zone comparison guide.
6. ⑥ Consolidate earned points and use them before they expireConsolidate all cashback into your main economic zone and use it before it expires. Expiry-prevention guide.

Common failures and how to avoid them

• Adding fish immediately after set-up and losing them all: The most common failure — adding fish before filter bacteria are established, then losing them to ammonia/nitrite poisoning. Cycle the tank for at least one to two weeks and confirm with a test kit that ammonia and nitrite read zero before adding any livestock.
• Overcrowding goldfish in a small tank: The guideline is 10–20 litres of water per goldfish. Overcrowding in a small container causes rapid water-quality collapse. Provide a tank with adequate volume and a high-capacity filter.
• DOA or weak-on-arrival livestock from online orders: Temperature stress in summer and winter, unsuitable packaging and delivery-day absence are the main causes. Be home for the delivery, inspect immediately on arrival, and confirm the shop's DOA compensation policy and claim deadline before ordering.
• Mixing incompatible species and suffering losses: Putting fish together without checking predation relationships, territorial behaviour or differing water-quality needs leads to one species being eaten or injured. Always verify compatibility with a specialist shop or reliable source before buying.
• Over-buying consumables for cashback: Stocking up on food, bacterial supplements and additives "because the cashback rate is good" and running out of time before the use-by date. Set purchase quantities based on your actual usage rate.
• Forgetting to route / points expiring: Skipping the routing step when buying initial equipment means losing significant cashback. Build the habit of routing through a point site before every purchase. Consolidate earned points into your main economic zone and use them before they expire. Expiry-prevention guide.

Mini glossary — key terms for aquarium point-earning

When thinking about point-earning alongside goldfish and tropical fish keeping, it helps to have the core vocabulary clear. Here are the essential terms together with the practical notes that matter most for buying and keeping decisions.

These are the foundational concepts for understanding aquarium point-earning. The non-negotiable starting point is building the water before any fish arrive, and welcoming only as many animals as you can genuinely care for to the end — online purchases of supplies and consumables pair well with cashback, and you can route bulk initial equipment purchases plus regular consumable orders through a point site. For livestock, however, the rule is always to choose based on shop reliability, the ability to check condition and DOA compensation — not on cashback or price.

Frequently asked questions