Care library / Health

Health guide, not a diagnosis · Serious if left

Slime-coat parasites (Costia, Chilodonella, Trichodina)

Also called costia, chilodonella, trichodina, ichthyobodo, slime disease

Signs

Grey-blue cloudy slime on the body
Rubbing, clamped fins
Fast breathing

Cause

Microscopic parasites that multiply when fish are stressed or water quality is poor. A microscope check confirms which one.

What to do

Improve water quality and treat with a broad anti-parasite medicine (formalin–malachite) or a salt treatment the species tolerates. Follow the full course.

If a fish is badly ill, talk to an aquatic vet.

Prevention

Quarantine; keep water clean and stable.

Medicines used for it

Always read the label first

Ich & velvet treatmentsParasite treatments

Aquarium saltSalt & water care

Species often affected

64 species

Cardinal tetraParacheirodon axelrodi

Moderate3 cm23–29 °C

Black neon tetraHyphessobrycon herbertaxelrodi

Easy3.2 cm20–28 °C

Black skirt tetraGymnocorymbus ternetzi

Easy7.5 cm20–26 °C

Serpae tetraMegalamphodus eques

Easy4 cm22–27 °C

X-ray tetraPristella maxillaris

Easy4.5 cm24–28 °C

Lemon tetraHyphessobrycon pulchripinnis

Easy3.8 cm22–28 °C

Congo tetraPhenacogrammus interruptus

Moderate8 cm23–28 °C

Glowlight tetraHemigrammus erythrozonus

Easy4 cm24–28 °C

Rummy-nose tetraPetitella rhodostoma

Moderate5 cm24–27 °C

Ember tetraHyphessobrycon amandae

Easy2 cm24–28 °C

Bloodfin tetraAphyocharax anisitsi

Easy5.5 cm18–28 °C

Emperor tetraNematobrycon palmeri

Easy4.2 cm23–27 °C

Penguin tetraThayeria boehlkei

Easy6 cm22–28 °C

Head and tail light tetraHolopristis ocellifera

Easy4.5 cm24–28 °C

Bleeding heart tetraMegalamphodus erythrostigma

Moderate6.1 cm22–28 °C

Green neon tetraParacheirodon simulans

Moderate2.5 cm24–27 °C

Buenos Aires tetraPsalidodon anisitsi

Easy13.2 cm18–28 °C

Silver dollarMetynnis hypsauchen

Hard18 cm24–28 °C

Spotted silver dollarMetynnis lippincottianus

Hard16.4 cm23–27 °C

Red hook silver dollarMyloplus rubripinnis

Hard41.5 cm23–27 °C

Diamond tetraMakunaima pittieri

Easy6 cm24–28 °C

Black phantom tetraMegalamphodus megalopterus

Easy3.6 cm20–28 °C

Red phantom tetraMegalamphodus sweglesi

Easy3.5 cm22–27 °C

Ornate tetraMegalamphodus bentosi

Moderate4.5 cm23–28 °C

Flame tetraHyphessobrycon flammeus

Moderate2.6 cm20–26 °C

Silvertip tetraHasemania nana

Easy5 cm23–28 °C

Colombian tetraHyphessobrycon columbianus

Easy6.5 cm22–27 °C

Dawn tetraHyphessobrycon eos

Red-eye tetraBario sanctaefilomenae

Easy7 cm22–26 °C

Gold tetraHemigrammus rodwayi

Easy5.5 cm24–28 °C

Blue tetraBoehlkea fredcochui

Moderate5.4 cm22–26 °C

Rainbow tetraNematobrycon lacortei

Easy3.6 cm22–28 °C

False rummynose tetraPetitella georgiae

Easy5 cm22–26 °C

Brilliant rummynose tetraPetitella bleheri

Easy5 cm23–26 °C

Flag tetraHyphessobrycon heterorhabdus

Easy3.6 cm20–26 °C

Mexican tetraAstyanax jordani

Easy12 cm20–25 °C

Yellow tetraHyphessobrycon bifasciatus

Easy4.7 cm20–25 °C

Blackline penguin tetraThayeria obliqua

Easy8 cm22–28 °C

Silver tetraCtenobrycon spilurus

Easy8 cm23–27 °C

Glass bloodfin tetraPrionobrama filigera

Easy6 cm23–27 °C

Sailfin tetraCrenuchus spilurus

Moderate7 cm24–28 °C

Yellow-tailed Congo tetraAlestopetersius caudalis

Moderate6.2 cm22–26 °C

Red-eyed tetraArnoldichthys spilopterus

Easy10 cm24–27 °C

Long-finned African tetraBryconalestes longipinnis

Moderate16.4 cm22–26 °C

Ansorge's neolebiasNeolebias ansorgii

Hard3.5 cm24–28 °C

One-striped African characinNannaethiops unitaeniatus

Moderate6.5 cm22–26 °C

Three-lined pencilfishNannostomus trifasciatus

Easy3.6 cm24–28 °C

Dwarf pencilfishNannostomus marginatus

Moderate3.5 cm23–28 °C

Coral red pencilfishNannostomus mortenthaleri

Moderate3 cm24–28 °C

One-lined pencilfishNannostomus unifasciatus

Easy4 cm24–28 °C

Splashing tetraCopella arnoldi

Moderate5.5 cm24–28 °C

Red-spotted copeinaCopeina guttata

Moderate7.6 cm23–28 °C

Silver hatchetfishGasteropelecus sternicla

Easy6.5 cm24–28 °C

Black-winged hatchetfishCarnegiella marthae

Easy3.5 cm24–28 °C

Giant hatchetfishThoracocharax stellatus

Easy7 cm24–28 °C

Striped headstanderAnostomus anostomus

Easy20 cm24–28 °C

Spotted headstanderChilodus punctatus

Moderate8 cm24–28 °C

High-hat headstanderAbramites hypselonotus

Easy14 cm22–28 °C

Ruby tetraAxelrodia riesei

Moderate2.1 cm24–28 °C

Royal tetraInpaichthys kerri

Easy3.5 cm24–27 °C