Fish Health & Care / Reading symptoms and treatment labels
A fish-care chart is useful when it helps you describe what has changed. It becomes less useful when every picture seems to point to a bottle. Use our two visual references in order: record the signs and check the water first, then compare the purpose and instructions of a treatment that fits the identified problem.
This guide focuses on freshwater aquarium observations and explains API MELAFIX and PIMAFIX label purposes. A marine or reef aquarium needs its own compatibility assessment.
Read the signs without jumping to a diagnosis
- Cotton-like patches: note their location and whether they are spreading.
- Frayed fins: compare the edge with an earlier photograph.
- Rubbing or scratching: record how often it happens and which fish are affected.
- A swollen body: photograph the fish from the side and above.
- Red streaks: note whether redness is in the fins, skin or both.
- Cloudy or swollen eyes: record whether one or both eyes have changed.
- Red sores: document the position and any worsening tissue damage.
- Mouth or back patches: describe texture and colour rather than naming a disease.
- Fast breathing: note surface-gasping, gill movement and how many fish are affected.
Similar appearances can arise from different problems. Eye changes, for example, can involve injury, parasites or other disorders. Swelling is also a sign rather than a complete diagnosis. The Merck Veterinary Manual fish-disorders overview explains why the environment and the whole fish matter alongside the visible lesion.
For white spots, fin damage and cottony growth in more detail, use our fish-health assessment checklist.
Check the aquarium before choosing a remedy
Write down actual ammonia, nitrite, pH and temperature results, including when you tested. Check filter flow and aeration, and list recent fish additions, water changes and products used. “The water looks clean” is not a water-test result. Our water-test guide helps you interpret the numbers together.
Severe gasping, loss of balance, rapid deterioration or sudden deaths need urgent aquatic veterinary help. Check aeration immediately and follow the surface-gasping first checks. Do not wait for a shopping order to arrive.
API MELAFIX and PIMAFIX: understand the listed purpose
The comparison below summarises manufacturer-listed uses. It does not establish the cause of a particular fish’s symptoms or guarantee that either product is suitable for that fish.
API MELAFIX
API lists MELAFIX for bacterial conditions including fin and tail rot, open wounds and eye cloud. The standard product shown in API’s current range is a freshwater remedy; API directs marine users to its separate marine formula. A damaged fin or cloudy eye alone does not confirm a bacterial infection.
API PIMAFIX
API lists PIMAFIX for fungal growth on fish bodies and fins, as well as certain bacterial infections, in freshwater and saltwater aquariums. Cotton-like growth is an observation to investigate, not a reliable way to select an antifungal without considering other causes.
What the comparison cannot tell you
It cannot identify parasites, explain severe swelling or determine the right response to breathing distress. Do not treat the two names as interchangeable options for every symptom. Before dosing, check the intended condition, actual water volume, fish species, aquarium type and exact concentration. Follow the current label for the course, water changes, filtration and equipment. Do not combine remedies by guesswork or copy a dose from a different bottle.
Match supplies to the job
These existing YoloLife products serve different roles; none is an automatic answer to every sign in the chart.
- Replacement-water preparation: API Stress Coat+ 473 mL (16 fl oz) is a water conditioner for chlorine and chloramine removal. It is not a substitute for diagnosing an infection.
- Aeration equipment: the MAYIN Hamburger Air Pump S supports suitable aeration equipment. Check installation, tubing and backflow protection; an air pump does not identify why a fish is gasping.
- Condition-specific treatment: Seachem ParaGuard has separate manufacturer guidance for certain external parasites and lesions. Check livestock compatibility first. It is not recommended for reef aquariums. Do not use it in tanks containing plants or invertebrates; medication-sensitive fish need specific advice. Read the full ParaGuard instructions before considering it.
Keep a care record that helps someone assess the problem
Bring together the fish species, tank volume, clear photographs, a short breathing or swimming video, test readings and a timeline of changes. List every product already added with its amount and time. Repeat photographs from the same angle so changes are easier to compare.
YoloLife can help you check product labels and equipment suitability; diagnosis and urgent treatment need an aquatic veterinarian. For prevention and a separate observation setup, read our quarantine guide. Return to Fish Health & Care for the symptom shortcuts, first checks and related guides.
Manufacturer purposes checked on 28 October 2026. Illustrations are educational references, not clinical diagnostic photographs. Always use the current instructions on the exact product you have.