Catfish & plecos

Barbel and mouth erosion

SignsCorydoras barbels shorten and dissolve, mouth tip red and raw, cannot find food

PreventionAvoid sharp-edged substrate; use fine sand. Siphon bottom debris once a week

Aeromonas infection

SignsRed hemorrhagic spots on the body, swollen belly, raised scales, redness at fin bases

PreventionLeave no uneaten food. Avoid overcrowding and reduce organic waste with water changes

Ich (white spot disease)

SignsWhite dots on body and fins, rubbing against the bottom or driftwood, clamped fins

PreventionAvoid sudden temperature swings; keep a stable 25–27°C. Quarantine newcomers 1–2 weeks in a separate container

Emaciation / starvation

SignsPleco belly sunken, eyes sunken, sluggish, backbone showing

PreventionEasily outcompeted by other fish. Feed sinking species-specific food after lights-out

Nitrite / ammonia poisoning

SignsRapid breathing near the surface, lying on side, dark-red gills, several fish weakening at once

PreventionLarge species produce a lot of waste. Use strong filtration and test strips weekly as a habit

Fungal infection (water mold)

SignsCotton-like white fluff on the skin or wounds, spreading from barbel bases or spine injuries

PreventionAvoid wounds from nets or spines. Avoid low temperatures and dirty water

Spines tangled in a net

PreventionScoop with a container or cup instead of a net. If you must use a net, use a fine-mesh vinyl one

First aidCut the net away underwater; never pull the spine free by force. If wounded, isolate in clean water and watch for fungus

Jumping out / falling

PreventionThey become active at night and jump. Use a gap-free lid with a weight and block cable holes

First aidPick up with wet hands and return to the tank. Even if lying still, do not give up for 30 minutes; turn aeration up

Fight wounds from tankmates

PreventionKeep plecos and large catfish alone. Separate any individual that rasps other fish with its sucker mouth

First aidIsolate the injured fish and let the wound heal in clean water. Consult a vet if red patches or cotton-like growth appear

Heater burns

PreventionBottom-dwelling fish easily touch the heater. Always fit a heater guard

First aidA white burned patch is an entry point for fungus. Isolate, keep the water clean, and see a vet the same day if it worsens

Salmonellosis

RouteHand-to-mouth after touching tank water, substrate or equipment

PreventionWash hands with soap after tank work. Do not wash equipment in the kitchen sink

Atypical mycobacteriosis

RouteBacteria in tank water enter through cuts on the hands

PreventionWear gloves when you have cuts on your hands. See a dermatologist if a swelling does not heal

Aeromonas infection

RouteEnters through spine punctures or cuts from a net

PreventionRinse spine wounds under running water and disinfect. If red and swollen, see a doctor and mention tank work

Secondary infection of spine punctures

RoutePectoral or dorsal fin spines pierce the hand

PreventionDo not grab with bare hands. If pierced, rinse under running water; see a doctor if pain or swelling persists

Food

• Corydoras: sinking tablets or frozen bloodworms once a day before lights-out
• Plecos: vegetable tablets, boiled vegetables and driftwood once a day
• Large catfish: mainly pellets; frozen fish or crustaceans 2–3 times a week to prevent obesity

Water

• Dechlorinated tap water. Keep 25–27°C and pH 6.5–7.5
• Change 1/3 of the water weekly; twice weekly for large species. Siphon bottom debris at the same time

Toys & play

• Pre-soaked driftwood for plecos (essential; they rasp and eat it)
• For Corydoras, fine sand with bloodworms buried for foraging
• For large catfish, a large pipe or shelter they can enter and leave

Nest, bed & hideout

• Hides such as pipes, driftwood or terracotta tubes that fully conceal the body
• At least one hide per fish. Choose wide entrances they cannot get stuck in

Bedding & litter

• Corydoras: a thin layer of smooth fine field sand or river sand
• Plecos: bare tank or coarse gravel so waste is easy to siphon
• Large catfish: bare tank as standard, to prevent swallowing substrate

Cage / housing material

Glass tank, or acrylic for large setups. Always a weighted lid

Size & space

Corydoras 60 cm+, plecos 90 cm+, large catfish 150 cm or more

Layout

• Spread hides across the back and sides, leaving a swimming lane
• Install the heater with a guard where the current flows
• Combine a strong canister or hang-on-top filter with aeration

Placement notes

• Check floor load capacity for large tanks and use a reinforced stand
• Avoid direct sunlight and vibration; turn lights off at night

Exercise, free-roam & walks

• They are active at night, so keep the hours after lights-out quiet
• All exercise happens in the tank. Large species need a tank width at least 3 times body length
• Do not remove from the tank even for cleaning. If you must, return within 30 minutes

Temperature & humidity

Temperature25–27°C. Japanese catfish tolerate 15–28°C, but sudden changes are dangerous

HumidityNo humidity control needed for aquatic life. Top up evaporated water

Summer & winter

• Summer: above 30°C use a cooling fan or chiller. Watch for oxygen shortage
• Winter: double up heater and thermostat. In a power outage, insulate with blankets

Nail trimming

No nail trimming. Instead, clean the substrate weekly to prevent abrasion wounds on barbels and belly

Brushing, skin & coat care

No brushing. To protect the slime coat, never touch with bare hands; move with a cup or container, water and all

Other care

Remove pleco driftwood monthly and clean off debris. Rinse filter media lightly in tank water; never replace all at once

Protection from predators

• A weighted lid that cats and children cannot open
• Separate large tankmates so they cannot swallow small Corydoras
• Net large outdoor tanks against birds and raccoons

Foreign-body ingestion

Large catfish swallow substrate, pebbles and heater parts whole. Use a bare tank and keep no small items inside. If it cannot regurgitate and the belly swells, consult a vet the same day

Being stepped on

Fish that jump out get stepped on in the dark. If you notice a jump at night, watch your step and pick it up with wet hands. The spines will pierce bare feet

Getting pinched

They enter gaps in hides or driftwood head-first and get stuck. Choose entrances much wider than the body; if stuck, do not pull; lift the whole hide out gently underwater

Falls

Dropping during cleaning breaks spines and damages the skin. Always move in a container with water. If dropped on the floor, pick up with wet hands, turn aeration up and observe

Escape

Night-time jumping is the main escape. Seal gaps with a lid and weight. Releasing a fish you can no longer keep into a river or pond is illegal; find a shop or rehoming service

Safe release procedure

1. Stop moving and return the fish to the water to calm it
2. If a spine is stuck in you, support the fish underwater and withdraw along the direction it entered
3. If bitten by a large catfish, wait for the mouth to open and gently release underwater
4. Spines tangled in a net: cut the net away with scissors underwater

After the release

Rinse puncture wounds under running water, gently squeeze out blood and disinfect. See a doctor if swelling or throbbing pain persists

What to tell the vet & what to bring

Bring tank size, number of fish, temperature, pH, nitrite level, last water-change date, diet and photos or video of symptoms. Phone first to confirm the clinic treats fish

Checking consciousness, breathing & heartbeat

• Gill-cover movement: normal is 60–120 per minute, slow and regular
• Critical if it does not flee when touched or lies on its side
• Observe barbels, fins, body color and the state of the slime coat

Stopping bleeding

• Fish bleeding is hard to stop underwater. Move to a clean isolation container
• Do not handle; keep dark and quiet. If cotton-like growth appears on the wound, treat for fungus
• If red patches spread, consult a fish-savvy vet the same day

Transport

• Place in a double plastic bag with tank water, fill with oxygen and insulate in a foam box
• Large species pierce bags with their spines; use a thick bag or lidded container and keep it dark