Ahh, the age-old question: "What's wrong with my fish?"
Below I have tried to help you answer this question by providing you with some of the most common fish diseases that can often affect our beloved aquarium inhabitants. They have been grouped by common symptoms, and questions you may ask the internet about your potentially sick fish. I hope it is helpful, and I wish your fish a quick recovery!
Q: “What is this white stuff on my fish?”
Ichthyophthirius multifiliis (Ich):
Credit: Aquarium Science
Also known as white spot disease, Ich is caused by a parasite that appears as small white cysts on the fish's skin and gills.
Signs & Symptoms:
Fish looks like it is covered in salt
Pure white cysts on fish’s scales
Uniform size of growths
Abnormal behavior; not eating
Inactivity or hiding
Treatment:
Quarantine sick fish(es) immediately to begin medication treatment
Raise temperature to at least 82 degrees F
Increase aeration of tank
Daily waterchanges
Medications: Hikari Ich-X
Prognosis:
Treatable depending on severity
Epistylis:
Credit: Aquarium Science
Epistylis is a disease commonly confused with ich. It can look almost identical to ich. Epistylis is typically fuzzy and translucent while ich is clearly defined and very white.
Signs & Symptoms:
Fuzzy, translucent growths on body; often in patches
Varying sizes of growths
Protrude further from fish than Ich
Commonly found near eyes
Treatment:
Quarantine sick fish(es) immediately to begin medication treatment
Lower temperature to at least 70 degrees F
Aerate the quarante tank aggressively
Daily waterchanges
Add below medications to their food
Medications: Hikari Ich-X (in case there is Ich as well), SeaChem Kanaplex or Fritz Maracyn 2 mixed into food
Prognosis:
Lethal in most cases; rarely treatable due to the speed at which it can kill the fish
Fungal Infections:
Credit: Aquarium Co-Op
Fungal infections can appear as cotton-like growth on a fish's body, fins, or mouth.
Signs & Symptoms:
Fuzzy, cotton-like white growth on fins, body, or mouth
Treatment:
Quarantine sick fish
Increase aeration of tank
Dose Aquarium Salt
Medications: SeaChem Kanaplex or Fritz Maracyn 2
Prognosis:
Easily treatable with medications, rarely lethal
Columnaris Disease (Cotton Wool Disease):
Credit: BLUEGent
Columnaris is a bacterial infection (F. columnare) that manifests as white patches on a fish's body, similar to cotton wool.
Signs & Symptoms:
Frayed and ragged fins
Ulcerations on the skin
Missing Gills
White or cloudy, fungus-like patches on the gill filaments
Sores or ulcers on the fins, head, and body
White area of affected tissue encircling the body, often called “saddleback”
Ulcers on the mouth and jaw in the most severe cases
Treatment:
Quarantine immediately
Antibiotic bath treatments (oxytetracycline, nitrofurazone, and kanamycin)
Potassium permanganate
Systemic antibiotic therapy may be needed in more severe infections
Medicated food and oral antibiotics
Prognosis:
Often fatal, even with proper treatment
“Why are my fish’s fins damaged?”
Fin Rot:
Credit: Chibi-Aquarium
This bacterial infection causes the fins of fish to deteriorate, often resulting in frayed or ragged fin edges.
Signs & Symptoms:
Visible damage to fins; frayed, deteriorated, missing completely
Treatment:
Quarantine sick fish immediately
Perform 50% water change on aquarium to prevent spreading
Dose original tank with the following medications, as well as the fish in quarantine
Medications: API Melafix, API Pimafix, SeaChem Kanaplex, or Fritz Maracyn 2
Prognosis:
Mildly difficult to treat; depends on severity and water conditions
Tail and Fin Biting:
Credit: REEF2REEF
Some fish species, like bettas, are prone to tail and fin biting due to stress or boredom. This can lead to fin damage and infections.
Signs & Symptoms:
Evidence of fresh (red) wounds occurring
Aggressive tank mate(s)
Overcrowded aquarium
Treatment:
Remove the bully if there is one
Upgrade to a larger tank
Quarantine injured fish and treat with medications
Medications: API Melafix and API Pimafix
Prognosis:
Easily treatable; not usually lethal for most fish species, depending on severity
“Why does my fish have wounds on its body?”
Hole-in-the-Head Disease (Hexamita):
Credit: The Planted Tank Forum
This disease causes small pits or lesions to form on the fish's head, giving it its name. It's often linked to poor water quality and nutrition.
Signs & Symptoms:
Skin lesions or missing scales/skin on head or surrounding area
Treatment:
Perform a 50% water change
Clean out dirty filters, vacuum gravel
Be cautious of overfeeding
Check equipment to ensure filters are working and clean
Medications: API Melafix, SeaChem Metroplex
Prognosis:
Easily treatable, can be fatal if not addressed immediately
Bacterial Infections:
Credit: JBL
Bacterial infections manifest in many ways, but common signs include a white film on the fish's body or fins, cloudy eyes, tattered fins, and hemorrhaging (bloody patches) or open sores (ulcers) on the body and mouth.
Signs & Symptoms:
Skin lesions on body
White film or slime on fish’s scales
Damaged fins
Fish missing scales
Cloudy Eyes
Treatment:
Perform a 50% water change
Quarantine sick fish
Clean out dirty filters, vacuum gravel
Medications: API Melafix, SeaChem Metroplex, Fritz Maracyn 2
Prognosis:
Easily treatable, can be fatal if not addressed immediately
Gill Flukes:
Credit: Aquarium Science
These parasites attach themselves to a fish's gills and can lead to respiratory problems and gill damage.
Signs & Symptoms:
Fish seems to be hyperventilating
Staying at the top of the tank, possibly gulping air
Visible parasites
Gill damage
Treatment:
Medications: SeaChem ParaGuard, Kordon CopperAid, SeaChem Cupramine, API Pimafix, Fritz ParaCleanse
Prognosis:
Treatable in most cases
Anchor Worm:
Credit: JBL
Anchor worms are parasitic copepods that attach to a fish's skin and can cause inflammation and tissue damage.
Signs & Symptoms:
Visible crustaceans climbing on fish
Inflamed tissues or open lesions
Treatment:
Medications: SeaChem ParaGuard, Kordon CopperAid, SeaChem Cupramine, API Pimafix, Fritz ParaCleanse
Prognosis:
Treatable in most cases
Fish Lice:
Credit: Aquarium Science
Fish lice are crustacean parasites that attach themselves to fish and can cause skin and scale damage.
Signs & Symptoms:
Visible bug-like parasites under scales, fins, and gills
Treatment:
Medications: SeaChem ParaGuard, Kordon CopperAid, SeaChem Cupramine, API Pimafix, Fritz ParaCleanse
Prognosis:
Treatable in most cases
Flukes:
Credit: Aquarium Science
Flukes are flatworm parasites that can attach to the skin and gills of fish, causing damage and irritation.
Signs & Symptoms:
Visible worms on fish’s scales, gills, or orafices
Treatment:
Medications: SeaChem ParaGuard, Kordon CopperAid, SeaChem Cupramine, API Pimafix, Fritz ParaCleanse
Prognosis:
Treatable in most cases
Velvet Disease:
Credit: Aquarium Science
Velvet is caused by a parasitic protozoan and appears as a fine golden or rust-colored dust on the fish's skin.
Signs & Symptoms:
Golden-brown dusty patches on fish’s scales
Treatment:
Medications: SeaChem ParaGuard,Kordon CopperAid, SeaChem Cupramine, API Pimafix, Fritz ParaCleanse
Prognosis:
Treatable, but can often be fatal if not addressed immediately
“Why is my fish bloated and acting weird?”
Internal Parasites:
Credit: Discus Fish
Various internal parasites can affect fish, leading to symptoms like weight loss, bloating, and abnormal behavior.
Signs & Symptoms:
Fish not eating normally
Acting abnormally
Worms in stool, stringy stool
Bloating or Weight Loss
Hiding constantly, usually near the heater or dark spot in the tank
Treatment:
Quarantine sick fish
Mix food with below medications
Medications: SeaChem Metroplex, Fritz ParaCleanse
Prognosis:
Treatable, but can be challenging
Dropsy:
Credit: Aquarium Science
Dropsy is a condition in which a fish's body swells, and its scales protrude. It's often a symptom of internal issues, such as organ failure or infection. It results in the swelling of a fish's body and scales, making the fish appear bloated.
Signs & Symptoms:
Swelling; bloated abdomen
Protruding scales due to swelling
Abnormal eating behaviors
Inability to swim normally; typically on its side, upside down, or laying on the bottom of the tank
Treatment:
Medications: SeaChem Kanaplex or Fritz Maracyn 2
Prognosis:
Not great; very difficult to treat especially in severe cases
“Why is my fish swimming upside down or on its side?”
Swim Bladder Disorder:
Credit: FishLab
Fish with swim bladder issues have difficulty controlling their buoyancy and may float or sink uncontrollably.
Signs & Symptoms:
Swimming abnormally, typically on its side or upside down
Bloating
Protruding scales
Not eating
Treatment:
Large fish like goldfish can be placed in a floating splint to help keep them upright
Specially formulated sinking foods, blanched green peas
Prognosis:
Hard to treat, often fatal
“What is wrong with my fish’s eye(s)?”
Pop-eye:
Credit: JBL
Pop-eye is a condition in which a fish's eyes become swollen and protrude from their sockets. It can be caused by various underlying issues, such as bacterial infections.
Signs & Symptoms:
Enlarged, puffy eyes
Eyes coming out of sockets
Can have cloudiness to them
Bumping into things, poor vision
Treatment:
Medications: SeaChem Kanaplex or Fritz Maracyn 2
Prognosis:
Difficult to treat, not usually fatal
Cloudy Eye:
Credit: British Colombia Aquarium Forums
Cloudy eye is a condition in which a fish's eyes become cloudy or appear whitish, often due to bacterial or environmental factors.
Signs & Symptoms:
Similar to cataracts
Cloudy eyes
Blue-ish gray haze
Treatment:
Medications: SeaChem Kanaplex or Fritz Maracyn 2
Prognosis:
Treatable, usually not fatal
“Why is my fish not eating?”
Likely a combination of one or more of the above!
Preventing fish diseases through proper aquarium maintenance, water quality management, and quarantine procedures for new fish is essential. If you suspect that your fish may have a disease, it's advisable to consult with a veterinarian or a knowledgeable aquarium specialist to determine the appropriate treatment. Good luck!
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