Internal Issues

Discussion in 'Fish Diseases & Treatments' started by Humblefish, May 19, 2019.

  1. Humblefish

    Humblefish Active Member

    Nov 9, 2018
    Likes Received:
    Internal Issues

    For simplicity's sake, there are 6 basic problems a marine fish may experience on the inside:

    1. Intestinal worms
    Symptoms: White stringy feces, pinched stomach, loss of color, fish eats voraciously but still seems to be losing weight.
    Treatment of choice: Praziquantel
    Alternative treatments: Fenbendazole, Levamisole, Piperazine

    2. Internal parasites/flagellates
    Symptoms: White stringy feces, pinched stomach, loss of color, fish eats voraciously but still seems to be losing weight. Flagellates are more virulent than worms, and thus can kill faster.
    Treatment of choice: Metronidazole
    Alternative treatments: Albendazole, Flubendazole and Mebendazole all show promise.

    3. Internal infections (bacteria)
    Bloating, and lumps or swollen areas on the body. Also, poor water quality can cause/aggravate an internal infection.
    Treatment of choice: Metronidazole combined with Neomycin Sulfate in a medicated fish food slurry can be a very good full spectrum internal/gut infection treatment, treating both aerobic and anaerobic bacteria.
    Alternative treatment: Seachem Focus claims to be an antibacterial polymer for internal infections of fish. The active ingredient found therein is nitrofurantoin.

    4. Swim bladder disorder
    Fish swims vertically with its tail up. Basically, the back half of the fish will seem more buoyant than the front half, and the fish will swim in a way to compensate for that. The fish may also stay near the surface of the water (or even float), unable to swim downwards. A protrusion (i.e. gas bubble) may be visible near the swim bladder area. In most cases, swim bladder disorders are caused by improper decompression of deep water species of fish.
    Treatment: If a gas bubble is present, you can lance the air out using a 30 gauge insulin syringe. For swim bladder infections, the following are possible treatment options:
    (1) Dose magnesium sulfate (Epsom Salt) at 1 tablespoon per 5 gallons.
    (2) Give the affected fish a 30 minute Methylene Blue bath.
    (3) Dose Metronidazole in conjunction with Neomycin. (You can food soak this combination as well.)

    5. Spinal injury
    Symptoms: Fish swims vertically with its tail down. Sometimes the fish just lays on the bottom of the tank; sometimes swims in a swirling motion. Most believe spinal injuries are caused when the fish jumps and hits a hard object (or swims/rams into one.) However, there is some evidence that internal flagellates and/or harmful bacteria which has migrated to the spinal canal may be contributing factors to spinal injuries. Wrasses seem most prone to spinal injuries, especially fairy & flasher wrasses.
    Treatment: The injury can heal if the damage is not too severe. Sadly, this is most often not the case. Dosing Metronidazole (for internal flagellates) + Erythromycin or Enrofloxacin (for bacteria) may help. If the fish is still eating, food soak metronidazole + neomycin as well.

    6. Fish constipation
    Bloated stomach, obvious anal obstruction, rectal prolapse, erratic swimming behavior. The fish will sometimes stay near the surface of the water, swimming in circles. Constipation is sometimes mistaken for a gas bubble in a fish's swim bladder (or vice versa.)
    Treatment options:
    Feed peeled boiled green peas (high in fiber)
    (2) Dose Epsom salt @ 1 tablespoon per 5 gallons (laxative)
    (3) Dose Kanamycin (Seachem Kanaplex) in a Quarantine Tank (diarrhea is a side effect of kanamycin)

    Internal parasites vs. intestinal worms - Since these can be difficult to distinguish due to near identical symptoms, it is best to always treat with praziquantel + metronidazole so both pathogens are covered. You can combine different medications (e.g. Prazipro + Seachem Metroplex), or API General Cure contains both.

    Does the color of the poop matter? - Yes! It has to be white. Brown stringy poop, for example, can just mean intestinal irritation which requires no treatment.


    Food soaking vs. dosing the water - Sometimes dosing the water with the above medication(s) can help clear an internal pathogen. After all, fish do drink the water, and their skin will absorb medications. However, I feel soaking fish food with medication(s) is the best way to treat internal problems for obvious reasons. Food soaking delivers meds directly into the gut where most internal pathogens live. In order to food soak, you should also use a binder (e.g. Seachem Focus, unflavored gelatin, agar) to prevent the medication from just leaching out into the water. Binding also makes the treatment reef safe. :) My recipe for food soaking dewormers can be found below:

    Using a shot glass:
    • 1 scoop (~ 1/8 teaspoon) of medication (General Cure or Fenbendazole + Metroplex)
    • 1-2 scoops Seachem Focus (this makes it reef safe + binds the medication to the food)
    • 1 Tbsp food (preferably pellets or frozen food)
    • A pinch of Epsom salt to help expel dead worms/parasites
    • A few drops of saltwater or fish vitamins
    • Stir until a medicated food slurry has been achieved.
    • Feed after soaking for 30 mins.
    • Refrigerate or freeze any leftovers for future use.
    • You can feed this mix 1-2 times per day. Not recommend to exceed 2 feedings per day with medicated food.
    • Feed daily for 2-3 weeks, or until poop returns to a solid brown or green color (no white).
    Final Thoughts - Due to the resilience of these critters, it is recommended to treat (or food soak) for a minimum of 10 days. However, it is not uncommon for symptoms to persist for up to 3 weeks. :eek: And just like with any other disease, you will sooner or later run up against a strain which seems resistant to the preferred treatment. In which case, you should seek out an alternative medication. (e.g. Using fenbendazole, levamisole or piperazine in lieu of praziquantel to treat stubborn intestinal worms.)
    Last edited: Jul 21, 2020
  2. nanoreefing4fun

    nanoreefing4fun Well-Known Member

    Mar 10, 2009
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    Arkansas, USA
    Reef Chronicle:
    Great Post - make Sticky
    Pancho75 and Humblefish like this.
  3. Uncle99

    Uncle99 Well-Known Member

    Aug 27, 2017
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    Province of Ontario, Canada
    Terrific humblefish!
    Great post....
  4. Pancho75

    Pancho75 Well-Known Member

    Nov 14, 2017
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    Super post @Humblefish!

    Thank you for sharing.

    Sent from my iPhone using Tapatalk
    Humblefish and nanoreefing4fun like this.
  5. ngoodermuth

    ngoodermuth New Member

    Feb 12, 2017
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    Great post! As usual :)

    Sent from my iPhone using Tapatalk
    Humblefish and nanoreefing4fun like this.
  6. Humblefish

    Humblefish Active Member

    Nov 9, 2018
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    Some new information:

    Fish with internal pathogens (white stringy poo) are usually afflicted by either internal flagellates (parasitic diplomonads) or intestinal worms. Most intestinal worms are going to be trematodes, cestodes or nematodes.

    The treatment of choice for internal flagellates is metronidazole, although food soaking chloroquine or flubendazole may be viable alternatives. Since those two drugs are often still available in countries (like the UK) where metronidazole requires a Rx.

    For intestinal worms, this is what treats what:

    1. Praziquantel: Treats trematodes & cestodes only.
    2. Piperazine: Treats nematodes only.
    3. Fenbendazole: Treats trematodes, cestodes and nematodes.
    So clearly, food soaking Fenbendazole + Metronidazole in a QT environment will give you the widest treatment coverage for internal issues. Using a drop or two of Dimethyl sulfoxide (DMSO) will help to fully dissolve Fenbendazole. DO NOT use Fenbendazole in a reef tank because it will kill corals (no matter how much Focus you use.) DO NOT use Piperazine in a reef tank. Food soaking General Cure (which contains prazi + metro) is still your best option in a reef tank because both medications are mostly reef safe.

    Alternatively, you could food soak General Cure + Piperazine (on alternating days) in QT to provide the same treatment coverage as food soaking Fenbendazole + Metronidazole.

    For those who are completely opposed to using medications, I am seeing good results just by food soaking magnesium sulfate (Epsom salt) to "flush" the pathogens out of the intestines. However, this won't help with diplomonads (e.g. Hexamita) that tend to migrate to other parts of the body (sensory pores, spinal column, etc.)

    I will figure out later how to incorporate this new information into the OP (sticky).
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