This reviewed buying guide covers 10 freshwater fish. A photograph appears only when the image shows the exact species alive in an aquarium or other suitable submerged setting and its reuse record is complete; the reviewed profile remains available without substitute imagery while a qualifying photo is sourced.
Use the guide at the retailer to compare breathing, posture, body condition, skin, fins, eyes, and behavior with what is normal for the species. Look at the whole sales system, ask about feeding and recent arrivals, and quarantine every new fish before it shares water or equipment with an established aquarium.
This is an observation guide, not a diagnosis. A fish that looks healthy can still carry pathogens, while transport, lighting, age, sex, and social position can change normal appearance and behavior.
Content transparency
AI-generated draft, human-reviewed publication
This guide was drafted with generative AI used to organize research and prepare an initial version. The AI output was not treated as an authority or source. Dan from the Simply Submerged Aquatics team reviewed the published guide for accuracy and completeness within the scope recorded below.
What the human review covered
- Species identities, scientific names, and public fish-selection copy
- Healthy signs, purchase warning signs, and diagnostic limitations
- Species-normal behavior and temperament distinctions
- Source records, image licences, and TankWise app statements
Key takeaways
- Watch the complete sales tank before choosing an individual fish.
- Compare breathing, posture, body condition, skin, eyes, fins, and response rather than relying on one sign.
- Allow for normal species behavior, including resting, hiding, schooling, feeding patterns, territorial display, and social position.
- Confirm the scientific identity and eventual aquarium needs before buying.
- Only approved exact-species aquarium photographs are shown; a reviewed profile remains available without an image when photography is pending.
- A healthy-looking fish still needs a suitable aquarium; compare it with your saved tank in TankWise before buying.
Store-side field guide
10 fish at a glance
Match the store label to the fish, then jump straight to its healthy and warning signs.
Bristlenose PlecoAncistrus sp.Endler's LivebearerPoecilia wingei
Three-spot GouramiTrichopodus trichopterus
Bloodfin TetraAphyocharax anisitsiClown KillifishEpiplatys annulatus
Elephantnose FishGnathonemus petersiiSalvini CichlidTrichromis salvini
Blue Peacock CichlidAulonocara stuartgranti
Bleeding Heart TetraHyphessobrycon erythrostigma
Parkinson's RainbowfishMelanotaenia parkinsoniCheck the sales tank before the fish
Watch before anyone taps the glass, feeds the fish, or reaches for a net. Compare breathing, posture, body condition, skin, fins, eyes, and behavior across the group rather than choosing only by color or activity.
Pause if a tankmate is dead, unable to balance, extremely thin, ulcerated, heavily spotted, covered in growth, or breathing with pronounced effort. Ask when the fish arrived, whether it has eaten, and whether nearby tanks share filtration.
A feeding response is useful evidence, but it does not prove that a fish is disease-free. Quarantine every new arrival separately and avoid sharing wet equipment with the established aquarium.
- Observe the group from a distance before selecting a candidate.
- Compare the candidate with several fish of the same species when possible.
- Confirm the store label and scientific identity.
- Ask about arrival date, feeding, treatment history, and shared filtration.
- Check the species against your aquarium in TankWise before purchase.
Bristlenose Pleco
Ancistrus sp.
What to notice
Review these species-specific points together: Full belly, intact mouth, clear eyes, correct identity and adult size.
Confirm that resting, hiding, bottom-feeding, nocturnal activity, barbel condition, and breathing behaviour are described in a species-appropriate way.
Endler's Livebearer
Poecilia wingei
Review these species-specific points together: Wasting, clamped fins, shimmying, hybrid or mislabelled stock.
Confirm that sex, pregnancy, courtship, persistent harassment, body condition, and shimmying are interpreted carefully.
Three-spot Gourami
Trichopodus trichopterus
What to notice
Review these species-specific points together: Skin sores, intact feeler fins, breathing, adult territorial behavior.
Confirm that normal surface air-breathing is distinguished from repeated gasping or breathing distress.
Bloodfin Tetra
Aphyocharax anisitsi
What to notice
Review these species-specific points together: Red fin color, full body, clear skin, active schooling.
Confirm that schooling, chasing, colour change, and social position are explained without treating every shy or subordinate fish as ill.
Clown Killifish
Epiplatys annulatus
Review these species-specific points together: Body weight, jaw and back condition, surface activity, jumping risk.
Confirm the species' normal posture, activity period, social behaviour, hiding, feeding response, and territoriality before labelling behaviour abnormal.
Elephantnose Fish
Gnathonemus petersii
What to notice
Review these species-specific points together: Full belly, uninjured chin organ, feeding response, social stress.
Confirm the species' normal posture, activity period, social behaviour, hiding, feeding response, and territoriality before labelling behaviour abnormal.
Salvini Cichlid
Trichromis salvini
Review these species-specific points together: Jaw or fin damage, body condition, clear skin, breeding aggression.
Confirm that territorial display, pair or group dynamics, mouthbrooding where relevant, and persistent bullying are clearly separated.
Blue Peacock Cichlid
Aulonocara stuartgranti
What to notice
Review these species-specific points together: Body weight, mouth and fin damage, color hormones or stress, male aggression.
Confirm that territorial display, pair or group dynamics, mouthbrooding where relevant, and persistent bullying are clearly separated.
Bleeding Heart Tetra
Hyphessobrycon erythrostigma
What to notice
Review these species-specific points together: Body depth, red shoulder mark, fin integrity, school behavior.
Confirm that schooling, chasing, colour change, and social position are explained without treating every shy or subordinate fish as ill.
Parkinson's Rainbowfish
Melanotaenia parkinsoni
What to notice
Review these species-specific points together: Body condition, mouth or scale damage, color development, active schooling.
Confirm that schooling, chasing, colour change, and social position are explained without treating every shy or subordinate fish as ill.
Sources and further reading
These references provide scientific or technical background and disclose how TankWise works. External references do not imply that every current TankWise catalog value was sourced from, or reviewed by, those organizations. See the checker methodology and known limits for that distinction.
- Selection of FishMerck Veterinary Manual
Veterinary-reviewed guidance on assessing a fish, its environment, skin, fins, eyes, movement, and alertness before purchase.
- Selecting a FishAmerican Veterinary Medical Association
Supports checking adult needs, body condition, breathing, behavior, and the wider sales system, while recognizing that a normal-looking fish may still carry disease.
- Pet Fish HealthRSPCA
Species-aware health context for appetite, breathing, alertness, eyes, fins, scales, and swimming.
- FishBase Species SearchFishBase
Scientific identity, distribution, biology, size, and cited species information used alongside other qualified sources.
- TankWise checker methodology and known limitsSimply Submerged Aquatics
The inputs, rules, safety limits, and uncertainty boundaries behind the TankWise aquarium comparison.
- Bristlenose Pleco species recordFishBase
Species reference for Bristlenose Pleco (Ancistrus sp.).
- Endler's Livebearer species recordFishBase
Species reference for Endler's Livebearer (Poecilia wingei).
- Three-spot Gourami species recordFishBase
Species reference for Three-spot Gourami (Trichopodus trichopterus).
- Bloodfin Tetra species recordFishBase
Species reference for Bloodfin Tetra (Aphyocharax anisitsi).
- Clown Killifish species recordFishBase
Species reference for Clown Killifish (Epiplatys annulatus).
- Elephantnose Fish species recordFishBase
Species reference for Elephantnose Fish (Gnathonemus petersii).
- Salvini Cichlid species recordFishBase
Species reference for Salvini Cichlid (Trichromis salvini).
- Blue Peacock Cichlid species recordFishBase
Species reference for Blue Peacock Cichlid (Aulonocara stuartgranti).
- Bleeding Heart Tetra species recordFishBase
Species reference for Bleeding Heart Tetra (Hyphessobrycon erythrostigma).
- Parkinson's Rainbowfish species recordFishBase
Species reference for Parkinson's Rainbowfish (Melanotaenia parkinsoni).
Frequently asked questions
Can a fish that looks healthy still carry disease?
Yes. Visual screening can identify reasons to pause, but it cannot prove that a fish is free of pathogens or parasites. Quarantine new arrivals and avoid sharing wet equipment with an established aquarium.
Should I buy from a tank containing a dead or visibly distressed fish?
Pause and ask what happened, whether the tanks share filtration, and what action the retailer is taking. Choosing another fish from the same water does not remove shared exposure.
Is unusual color, hiding, or resting always a sign of illness?
No. Lighting, transport, age, sex, social position, and species-normal behavior can change appearance and activity. Review breathing, posture, body condition, skin, fins, eyes, and the condition of the whole tank together.
Why does this guide include 10 fish rather than ten?
Only fish with a licensed live or submerged exact-species reference photograph were included. Fish awaiting suitable photography remain unpublished instead of being represented by stock or substitute species.
Where does TankWise fit?
This guide helps screen the individual fish. TankWise then compares the species' needs with your aquarium, water, and current livestock. It does not diagnose illness or guarantee compatibility.