• Look at the poop  

       Medium to short chunky poop or poop the color of
       the food = Good

       Long Thin Poop = not eating well, usually
      stress related  

       Thick long = a little constipated or overfeeding and
       the food is moving through the fish too quickly and
       doesn't have time to be digested.  

       Zig Zag/clear long = reabsorbed eggs  

       Thin White = usually this is a sign of internal infection
      (unless white foods are being fed)  

       Clear  with bubbles = not eating well if at all  

       Dark, sausage like, long mucousy casing, floating
       suspended by bubbles = gas trapped in floating
       foods, foods are being fermented by gas causing
      bacteria, fish are eating bubbles  

       No poop seen, but water is tinged brown = diarrhea
      possibly with blood. this is an ominous sign.

       Feces that float have entrapped air, either from the
       food, or due to bacteria fermenting the food and
        producing gas. Because there is no connection
       between the digestive system and the air or swim
       bladder in Goldfish, eating air bubbles may cause
​       air bubbles in feces.

  • Determining what is the causative agent (what to treat for) is the diagnosis part. Each diagnostic feature rarely stands alone, rather it is part of a package of signs and symptoms.

  • SO IN GENERAL, thin white poop is bacteria. BUT if the head is down, it may be parasites or bad food, so both the slime coat and food has to be checked. But if the feces are thin, white but with bubbles in the feces AND the fish are seen excessively eating bubbles at the surface, this has been correlated to an internal infection with columnaris.

  • Diarrhea in fish is often seen as a brownish tinge in the water. Bad foods with toxins can cause diarrhea. Fish wobble or spin in the water as they lose electrolytes (which cause the neurological symptoms.)

  • So treatment with anti-parasitic or antibiotic food depends on the whole picture, rather than any one diagnostic feature.​



If you do not have access to a microscope to check for parasites and bacteria or you feel like it is way over your head then try this simpler technique for diagnosing your fishes health.

  • Isolate suspect fish in a separate tank away from other fish.

  • Wet both hands.

  • Hold the fish upside down in your left hand if you are right handed. This cuts down on the struggling. Hold the fish over the tank so if they slip out of your hands, they splash down rather than go splat. If the head and gills of the fish is in the water, they are less likely to struggle.  

  • Check the gills. Use the right thumb nail to gently lift the gill cover just enough to see the gills. A light is very good for doing physicals on fish. 

       Gills that are bright cherry red are healthy.  

       Gills that are dark red indicate either the water is
       toxic (ammonia, nitrites, nitrates, metals, chlorine,
       medication) or there is a parasitic infection.  

       Gills that are light pink indicates anemia. This can be
       due to a bacterial infection or the toxicity of

       Gills that are glopped together and/or looks like
        raw hamburger indicates a parasite  

  • Push gently on the belly of the fish in front of the anal port  A belly that is normal is like pushing a finger into muscle of upper arm when muscle is relaxed  A belly that is mushy (like poking finger into fat on stomach) can be due to unreleased or infected eggs, or an internal parasitic or bacterial infection  A belly that is hard indicates a possible impaction  A red anal port could be internal Columnaris or other bacterial infection  Check to see if anything is leaking out of the anal port when the sides of the fish is gently pressed. Leaking fluid indicates infection or toxins with diarrhea (see below).  

  • look at the fish from the side when they are swimming. There should be no dumpiness near the anal port, but be a nicely rounded curve up to the anal fins and tail. Dumpiness is an indication of internal infection.  Look in the mouth by bringing the fish up to the surface of the water. A fish will automatically open their mouth as they break the surface. Red on the upper side of the mouth also indicates an internal infection. White strings around the mouth is an indication of Columnaris infection. 

  • After letting go of the fish, notice whether the slime coat is:  Thick or mucousy when you rub your fingers together. In general, parasites stimulate the production of thick slime coats. However, toxins can also do this.  "Dry" or a lack of a slime coat is symptomatic of Columnaris.