Platy in an aquarium. Photo: Photograph by Jere Kyyrö. Uploaded by Rasvis.. View source · CC BY-SA 3.0 · Downloaded provider thumbnail or original as supplied; no further crop or colour change.
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.
Photographs are reference examples, not evidence that an individual fish is healthy. Profiles without a verified aquarium photograph remain text-only.
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. Simon from the Simply Submerged Aquatics team reviewed the published guide for accuracy and completeness within the scope recorded below.
Human reviewerSimonTankWise product lead and freshwater aquarist
Last reviewed
What the human review covered
Fish-selection text and identity notes reviewed by Simon.
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.
Platy
Xiphophorus maculatus
Reference photo: Photograph by Jere Kyyrö. Uploaded by Rasvis.. View original · CC BY-SA 3.0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
German Blue Ram
Mikrogeophagus ramirezi
Reference photo: Eric Mengel. View original · Public domain. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Congo Tetra
Phenacogrammus interruptus
Reference photo: André Karwath aka Aka. View original · CC BY-SA 2.5. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Pictus Catfish
Pimelodus pictus
Reference photo: 5snake5. View original · CC0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Forktail Blue-eye
Pseudomugil furcatus
Reference photo: Dirk Godlinski. View original · CC BY-SA 3.0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Horseface Loach
Acantopsis dialuzona
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Silver Dollar
Metynnis argenteus
Reference photo: Greg Hume. View original · CC BY-SA 4.0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Yellow-tail Acei
Pseudotropheus sp. “acei” (aquarium trade name)
Acei is an aquarium trade name. A taxonomic treatment places acei sensu Konings under Pseudotropheus elegans, but a trade label alone does not establish the identity of every stock. Confirm the yellow-tailed form and supplier identity.
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Striped Raphael Catfish
Platydoras armatulus
Reference photo: Kacper Aleksander. View original · CC BY-SA 4.0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
Rosy Red or Fathead Minnow
Pimephales promelas
Reference photo: Rankin1958. View original · CC BY-SA 3.0. Downloaded provider thumbnail or original as supplied; no further crop or colour change
What to notice
Compare this fish with several of the same species when possible. Ask the retailer about feeding, arrival time and the behavior you observe. Brief hiding or a social display is different from persistent exclusion, injury or inability to feed; interpret it alongside breathing, body condition and the whole sales tank.
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.
Supports checking adult needs, body condition, breathing, behavior, and the wider sales system, while recognizing that a normal-looking fish may still carry disease.
Page 174 places acei sensu Konings 2007 under P. elegans; does not authenticate every aquarium trade stock.
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.
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.
TankWiseFreshwater aquarium companion
Check the fish. Then check the fit.
TankWise screens what your fish needs first, then compares against your aquarium, water, and current livestock before you buy.
PlatyXiphophorus maculatus
German Blue RamMikrogeophagus ramirezi
Congo TetraPhenacogrammus interruptus
Pictus CatfishPimelodus pictus
Forktail Blue-eyePseudomugil furcatusHorseface LoachAcantopsis dialuzona
Silver DollarMetynnis argenteusYellow-tail AceiPseudotropheus sp. “acei” (aquarium trade name)
Striped Raphael CatfishPlatydoras armatulus
Rosy Red or Fathead MinnowPimephales promelas,_2017.jpg){kind=link}
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