How to Pick Healthy Fish at the Store: What to Look For

Why Selection Matters
Red Flags: When to Walk Away
Green Flags: Signs of a Good Shop
Inspecting Individual Fish
Species-Specific Selection Tips
Timing Your Purchase
Quarantine After Purchase
Frequently Asked Questions

Why Selection Matters

Choosing healthy fish at the shop is one of the most important skills an aquarist can develop. A sick fish introduced to an established tank can spread disease to every other inhabitant, potentially wiping out a community you have spent months building. In Singapore, where aquarium shops range from small neighbourhood stores to large warehouse-style outlets, the quality of fish varies enormously.

The good news is that identifying healthy versus unhealthy fish is not difficult once you know what to look for. A few minutes of careful observation before purchasing saves you from days or weeks of treating sick fish at home.

Red Flags: When to Walk Away

These warning signs suggest that fish from a particular shop or tank are risky purchases. One or two minor issues might be acceptable, but multiple red flags mean you should buy elsewhere.

Dead Fish in the Display Tanks

An occasional dead fish is unavoidable in any shop that handles thousands of fish, but multiple dead fish across several tanks indicates systemic problems with water quality, disease management or neglect. If you see dead fish that have clearly been there for a while (white, fuzzy or decomposing), the shop is not monitoring their stock closely enough.

Cloudy or Foul-Smelling Water

Shop tanks should have clear water. Slight tinting from tannins (brownish water from driftwood) is fine, but milky white or green cloudiness indicates bacterial blooms or algae problems, both of which suggest poor water management. If you can smell the tanks from a distance, something is wrong.

Lethargic Fish Across Multiple Tanks

Fish in a well-maintained shop are active and alert. If you notice fish sitting on the bottom, hiding in corners or barely moving across multiple tanks, the shop likely has water quality issues or a disease outbreak. Individual lethargic fish might be old or settling in, but widespread lethargy is a red flag.

Visible Disease

Ich (white spots), fin rot, fungus (cotton-like growths) or velvet (gold dust on skin) in display tanks means those pathogens are present in the shop’s water system. Many shops run connected filtration systems, so disease in one tank can spread to others. If you see sick fish in any tank, be cautious about buying from that shop, even from apparently healthy tanks.

Severely Overcrowded Tanks

While shop tanks hold more fish per litre than home aquariums (due to heavy filtration and frequent water changes), extreme overcrowding causes stress, aggression and disease. If fish cannot swim without bumping into each other, conditions are too crowded.

Green Flags: Signs of a Good Shop

Active, Alert Fish

In a well-maintained shop, fish are swimming actively, exploring their surroundings and responding to movement outside the tank. Schooling fish should be schooling. Territorial fish should be showing normal territorial behaviour. Activity and alertness indicate good health and low stress.

Bright, Vivid Colours

Healthy fish display full, vibrant colouration. Faded or washed-out colours often indicate stress, illness or poor diet. Male fish in particular should show strong colouration. If a tank of cardinal tetras has dull, barely visible neon stripes, something is off.

Fish Eating Eagerly

If you can observe a feeding, this is the best indicator of health. Healthy fish rush to eat and compete for food. A fish that ignores food while others eat eagerly is likely stressed or sick.

Clean Tanks and Equipment

Glass should be reasonably clean (slight algae is normal), filters should be running, air stones should be bubbling, and there should be no excessive debris on tank floors. This indicates regular maintenance and attention to detail.

Knowledgeable Staff

Good shops have staff who can answer questions about species compatibility, water parameters and care requirements. If a staff member recommends a fish without asking about your tank size, existing inhabitants or experience level, be cautious. If they warn you against a purchase because it is not suitable for your setup, that is a shop that cares about fish welfare more than a quick sale.

Inspecting Individual Fish

Once you have decided a shop is trustworthy, inspect individual fish before asking staff to bag them. Here is a head-to-tail checklist.

Eyes

Good: Clear, bright, same size on both sides
Bad: Cloudy, bulging (pop-eye), sunken, different sizes

Fins

Good: Fully spread, intact edges, no tears or fraying
Bad: Clamped tight against body, ragged edges, reddened tips, missing chunks

Body

Good: Smooth, even colouration, well-proportioned, no visible parasites
Bad: White spots, gold dust, cotton-like growths, red sores, raised scales (pinecone appearance), lumps or bumps

Belly

Good: Slightly rounded, proportionate to body
Bad: Sunken (wasting, possible internal parasites), extremely bloated (dropsy, overfeeding or internal issues)

Behaviour

Good: Swimming normally, maintaining position in water column, alert to surroundings
Bad: Listing to one side, spiralling, gasping at surface, scratching against objects (flashing), hiding constantly

Quick Inspection Table

Feature	Healthy Sign	Warning Sign
Eyes	Clear and bright	Cloudy, bulging or sunken
Fins	Spread and intact	Clamped, torn or reddened
Body surface	Smooth, no spots	White spots, gold dust, sores
Body shape	Well-proportioned	Sunken belly or extreme bloating
Swimming	Active and balanced	Listing, gasping or lethargic
Colour	Vivid and consistent	Faded, blotchy or grey patches

Species-Specific Selection Tips

Tetras and Rasboras

Buy from tanks where the fish are schooling actively. Avoid any tank where multiple fish are sitting at the bottom or swimming erratically. Check for white spots carefully, as ich is common in tetra shipments. Purchase a group of at least 6-8 at once from the same tank to reduce acclimation stress.

Bettas

Bettas in shops are usually kept in individual cups or small containers. Look for bettas that are alert and flare when you approach. Avoid bettas with clamped fins, visible fin rot or those lying at the bottom of their cup. Colour should be rich and consistent. Slight fin curling in long-finned varieties is normal and not a health concern.

Corydoras

Healthy corydoras are active bottom foragers that regularly dart to the surface to gulp air (this is normal behaviour, not a sign of distress). Avoid specimens with red, irritated barbels (whiskers), which indicate poor substrate conditions. Their bellies should be gently rounded, not concave.

Shrimp

Active shrimp are constantly grazing and moving. Avoid shrimp that are motionless for extended periods or have a pink or milky discolouration. When selecting cherry shrimp, pick from a tank with consistent colouration. Check for scutariella (small white parasites on the rostrum) which are common in imported shrimp batches.

Timing Your Purchase

When you buy matters almost as much as what you buy.

Best Days to Buy

Weekday visits are preferable. Shops are less crowded, staff have more time to help you select fish carefully, and the fish are calmer without weekend crowds tapping on glass and creating commotion.

After New Shipments Have Settled

Fish that have just arrived from importers are stressed from transport and more likely to be carrying latent diseases. Ask shop staff when their latest shipment arrived. Ideally, buy fish that have been in the shop for at least 3-5 days, giving them time to settle and allowing any transport-related illnesses to become visible.

Most Singapore fish shops receive shipments on Mondays or Tuesdays. Buying on Thursday or Friday gives new arrivals a few days to settle while ensuring the stock is still fresh and well-stocked.

Avoid Public Holidays and Sale Events

Large crowds stress fish. Shop staff are rushed and may net carelessly. Tanks may be depleted of the best specimens. Visit during normal trading hours on a quiet day for the best experience.

Quarantine After Purchase

Even fish from the best shops can carry latent diseases. A quarantine period protects your existing tank inhabitants.

Set up a simple quarantine tank: 20-30 litres with a sponge filter, heater (if needed) and a hiding spot
Keep new fish in quarantine for 2-4 weeks before adding them to your main tank
Observe for signs of disease daily during quarantine
Treat any issues that appear before introducing the fish to your display tank

Many hobbyists skip quarantine because it seems like extra effort. But one diseased fish can infect an entire tank. The cost of a simple quarantine setup is far less than treating a full tank of sick fish or, worse, losing an entire community.

Frequently Asked Questions

Should I buy fish online or from a physical shop in Singapore?

Both options have merit. Physical shops let you inspect fish before buying, which is the biggest advantage. Online sellers in Singapore (many operate on Carousell or through Facebook groups) often have rarer species and may offer competitive prices. If buying online, choose sellers with strong reviews, ask for photos or videos of the actual fish you are buying, and check their live arrival guarantee policy.

Is it bad to buy fish from a shop with one sick fish in a tank?

One sick fish in an otherwise clean, well-maintained shop is not necessarily a dealbreaker, but avoid buying from that specific tank. If the shop uses a shared filtration system, be more cautious. If multiple tanks have sick fish, buy elsewhere. The key is whether the shop has noticed and is treating the problem. Ask staff about it. A good shop will be transparent.

How do I transport fish home safely in Singapore’s heat?

Singapore’s ambient temperature of 30-34 degrees Celsius during the day can overheat bagged fish quickly, especially in a car without air-conditioning. Ask the shop to double-bag with plenty of air space. Place bags in an insulated bag or cooler box for the journey. Go straight home after purchase, do not stop for errands. Float the sealed bag in your tank for 15-20 minutes to equalise temperature before releasing the fish.

Can I return a fish that gets sick after I buy it?

Return policies vary by shop. Some Singapore fish shops offer a short guarantee period (24-72 hours) for fish that die or show signs of illness. Always keep your receipt and ask about the return policy before purchasing. Be aware that once a fish is in your tank, proving it was sick at the time of purchase becomes difficult, which is another reason quarantine is so valuable.

Starting a new tank and want to stock it right? Our guide to the best fish for planted aquariums helps you choose species that thrive together in Singapore’s conditions.

If you prefer to leave species selection to the experts, our custom aquarium service includes curated livestock packages with healthy, quarantined fish sourced from trusted suppliers. Visit Gensou at 5 Everton Park, Singapore, or contact us to discuss your aquarium project.

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