Koi Fish Symptoms
Browse 54 guides from veterinary sources about koi fish symptoms.
Female Koi Full of Eggs: Normal Swelling or Egg-Binding?
Female koi can look swollen when carrying eggs, but belly enlargement can also signal egg-binding, dropsy, infection,...
Read more →Koi Fish Aggression: Why Your Koi Is Chasing, Bumping or Attacking
Koi chasing or bumping can be breeding behavior, crowding, or poor water quality. Learn when to monitor, when to see...
Read more →Koi Fish Anchor Worms: Visible Parasites, Redness & What to Do
Visible thread-like parasites on koi may be anchor worms. Learn signs, urgency, treatment options, home care, and...
Read more →Koi Fish Bleeding: Blood From the Body, Gills or Wounds
Koi fish bleeding can signal trauma, ulcers, parasites, or poor water quality. Learn when to see your vet, likely...
Read more →Koi Fish Breeding Tubercles: Normal Spawning Sign or Something Else?
Koi breeding tubercles are often a normal spawning sign in males, but white bumps can also signal disease. Learn when...
Read more →Koi Fish Clamped Fins: What It Means & When to Act
Koi clamped fins often signal stress, poor water quality, or disease. Learn urgent warning signs, vet care options, and...
Read more →Koi Fish Cloudy Eyes: Injury, Infection or Water Quality Problem?
Cloudy eyes in koi can point to injury, infection, or poor water quality. Learn when to monitor, when to call your vet,...
Read more →Koi Fish Constipation: Signs, Causes & Safe Next Steps
Koi fish constipation can look like bloating, poor appetite, or trouble swimming. Learn common causes, when to see your...
Read more →Koi Fish Drooling or Mouth Mucus: What It Means & When to Worry
Koi fish drooling or mouth mucus can signal water quality stress, parasites, or infection. Learn when to monitor, when...
Read more →Koi Fish Eating Less Than Usual: Common Causes & When to Call for Help
Koi eating less can signal cold water, poor water quality, parasites, or disease. Learn common causes, red flags, vet...
Read more →Koi Fish Erratic Swimming: Stress, Parasites, Toxins or Illness?
Koi fish swimming erratically may signal low oxygen, poor water quality, parasites, toxins, or serious illness. Learn...
Read more →Koi Fish Excess Slime Coat: Why Your Koi Looks Slimy or Milky
Koi with a slimy or milky look may have water quality stress, parasites, or skin irritation. Learn when to monitor,...
Read more →Koi Fish Eye Redness: Irritation, Injury or Infection?
Koi eye redness can stem from water quality, injury, parasites, or infection. Learn when to monitor, when to see your...
Read more →Koi Fish Fin Rot: Signs, Causes & When to Seek Help
Koi fin rot often starts with frayed, reddened fins and poor water quality. Learn causes, warning signs, treatment...
Read more →Koi Fish Flashing or Flicking: Causes, When to Worry & What to Do
Koi flashing or flicking can signal parasites, poor water quality, or gill irritation. Learn urgent signs, vet care,...
Read more →Koi Fish Floating: Buoyancy Issue, Low Oxygen or Serious Illness?
Koi floating at the surface can mean low oxygen, gas bubble disease, constipation, or serious illness. Learn when to...
Read more →Koi Fish Fungus: Cottony Growths, White Tufts & What to Do
Koi fish fungus often looks like white cottony tufts. Learn common causes, when to see your vet, treatment options, and...
Read more →Koi Fish Gasping at the Surface: Low Oxygen or Serious Illness?
Koi gasping at the surface can signal low oxygen, ammonia, nitrite, or gill disease. Learn when to see your vet and...
Read more →Koi Fish Head Down Tail Up: Buoyancy Problem or Serious Illness?
Koi floating head down tail up can signal buoyancy trouble, poor water quality, infection, or organ disease. Learn when...
Read more →Koi Fish Hiding: Stress, Illness or Normal Behavior?
Koi fish hiding can be normal or a sign of stress, poor water quality, parasites, or illness. Learn when to monitor at...
Read more →Koi Fish Isolating From the Group: Causes & Next Steps
Koi isolating from the group can signal water quality trouble, stress, parasites, or infection. Learn urgent signs, vet...
Read more →Koi Fish Jumping: Stress, Parasites or Poor Water Quality?
Koi fish jumping can signal stress, parasites, low oxygen, or toxic water. Learn when to monitor, when to see your vet,...
Read more →Koi Fish Keeping Mouth Open: Breathing Trouble, Mouth Injury or Disease?
Koi holding the mouth open can signal low oxygen, poor water quality, gill disease, parasites, or injury. See your vet...
Read more →Koi Fish Lethargy: Causes, When to Worry & What to Do
Koi fish lethargy can signal low oxygen, ammonia, parasites, or infection. Learn urgent warning signs, vet care...
Read more →Koi Fish Loss of Balance: Causes, Red Flags & Immediate Steps
Koi fish loss of balance can signal water quality trouble, swim bladder disease, parasites, or infection. Learn red...
Read more →Koi Fish Lumps or Growths: Tumor, Cyst, Carp Pox or Infection?
Koi fish lumps can be carp pox, infection, cysts, or tumors. Learn what to watch for, when to see your vet, and...
Read more →Koi Fish Missing Scales: Injury, Parasites or Infection?
Koi missing scales can come from pond injury, parasites, or skin infection. Learn when to monitor, when to see your...
Read more →Koi Fish Not Eating: Causes, When to Worry & What to Do
Koi fish not eating? Learn common causes, urgent warning signs, vet care options, home steps, and realistic 2026 U.S....
Read more →Koi Fish One Gill Not Moving: Gill Injury, Infection or Parasites?
One koi gill not moving can signal injury, poor water quality, infection, or parasites. Learn when to monitor, when to...
Read more →Koi Fish Pale Gills: Anemia, Shock or Water Problem?
Koi with pale gills may have anemia, severe stress, gill disease, or dangerous water quality trouble. Learn when to see...
Read more →Koi Fish Pineconing: Why Scales Stick Out & When It’s an Emergency
Koi fish pineconing usually means dangerous fluid buildup from infection, organ failure, or poor water quality. Learn...
Read more →Koi Fish Popeye: Bulging Eye Causes, Severity & What to Do
Koi fish popeye can signal trauma, infection, or dangerous water problems. Learn causes, urgency signs, vet care, home...
Read more →Koi Fish Rapid Breathing: Causes, Red Flags & What to Check First
Koi breathing fast can signal low oxygen, ammonia, gill parasites, or infection. Learn red flags, first checks, vet...
Read more →Koi Fish Red or Inflamed Gills: What It Means & What to Do
Red or inflamed gills in koi can signal poor water quality, parasites, or infection. Learn urgent signs, vet care, home...
Read more →Koi Fish Red Sores: Causes, Severity & What to Do Next
Koi red sores can signal ulcers, infection, parasites, or water-quality trouble. Learn when it is urgent, what your vet...
Read more →Koi Fish Red Streaks in Fins: Stress, Septicemia or Water Quality?
Red streaks in koi fins can signal water quality stress, injury, parasites, or septicemia. Learn when to monitor, test...
Read more →Koi Fish Rubbing Head or Body: Parasites, Irritation or Water Problems?
Koi rubbing or flashing can point to parasites, skin irritation, or poor water quality. Learn when to monitor, test...
Read more →Koi Fish Sinking: Why Your Koi Can’t Stay Upright or Swim Normally
Koi fish sinking or rolling over can signal water quality trouble, swim bladder disease, infection, or trauma. Learn...
Read more →Koi Fish Sitting on the Bottom: Normal Resting or a Sign of Illness?
Koi sitting on the bottom can be normal in cool water, but it may also signal poor water quality, low oxygen, stress,...
Read more →Koi Fish Skin Discoloration: Pale, Dark, Red or Unusual Color Changes
Koi skin discoloration can signal water quality problems, parasites, ulcers, or stress. Learn when to monitor at home...
Read more →Koi Fish Skin Sloughing Off: Causes, Risks & What to Do
Koi skin sloughing can signal poor water quality, parasites, infection, or injury. Learn urgent warning signs, vet care...
Read more →Koi Fish Spawning Injury Signs: Scale Loss, Bruising, Exhaustion & When to Help
Koi can lose scales, bruise, and become exhausted after spawning. Learn what is normal, warning signs, home care, vet...
Read more →Koi Fish Spinning in Circles: Neurologic Problem, Distress or Toxin Exposure?
Koi spinning in circles can signal ammonia toxicity, severe stress, infection, or neurologic disease. Learn when to see...
Read more →Koi Fish Spitting Out Food: Mouth Problem, Stress or Illness?
Koi spitting out food can point to mouth injury, poor water quality, stress, or disease. Learn when to monitor at home...
Read more →Koi Fish Stringy Poop: Parasites, Not Eating or Digestive Trouble?
Koi fish stringy poop can point to fasting, stress, parasites, or water quality trouble. Learn when to monitor, when to...
Read more →Koi Fish Sudden Death Warning Signs: Symptoms Owners Miss Before a Crash
Koi often show subtle warning signs before a crash. Learn the symptoms pet parents miss, urgent red flags, likely...
Read more →Koi Fish Swimming Sideways: Swim Bladder Problem, Weakness or Distress?
Koi swimming sideways can signal buoyancy trouble, poor water quality, infection, or neurologic disease. Learn urgent...
Read more →Koi Fish Swimming Upside Down: Causes, Emergency Signs & What to Do
Koi swimming upside down can signal buoyancy trouble, poor water quality, or serious illness. Learn emergency signs,...
Read more →Koi Fish Swollen Belly: Causes, Dropsy vs. Eggs & What to Do
Koi with a swollen belly may have eggs, constipation, fluid buildup, or infection. Learn dropsy warning signs, vet care...
Read more →Koi Fish Ulcers: Causes, Treatment Basics & When It’s an Emergency
Koi fish ulcers can signal infection, parasites, or poor water quality. Learn causes, treatment basics, emergency...
Read more →Koi Fish Vomiting or Regurgitating Food: Causes & What to Do
Koi spitting up food can signal overfeeding, cold water, poor water quality, or disease. Learn when to monitor at home...
Read more →Koi Fish Weight Loss: Why Your Koi Looks Thin or Wasted
Koi fish weight loss can signal parasites, poor water quality, or chronic disease. Learn when to monitor at home and...
Read more →Koi Fish White Patches: Fungus, Mucus Coat or Skin Disease?
Koi white patches can mean fungus, excess mucus, parasites, or viral skin disease. Learn what to watch for, when to...
Read more →Koi Fish White Spots: Ich, Parasites, Fungus or Something Else?
White spots on koi can mean ich, carp pox, fungus, or water-quality stress. Learn what signs matter, when to call your...
Read more →