How-to: Gavage medication to a fish

*I AM NOT A VETERINARIAN.  ALL MEDICATIONS SHOULD BE ADMINISTERED WITH VETERINARY SUPERVISION AFTER APPROPRIATE EXAM AND DIAGNOSIS.  DOSES PROVIDED ARE FOR REFERENCE ONLY FROM AVAILABLE OVER-THE-COUNTER LITERATURE.*

We've all had fish that won't eat medicated food.  This is likely due to the fact that the medications themselves taste terrible; and I know, I've taken most of them.  However their recovery often hinges on getting those meds into their digestive tract, and suspended medications in the water column often cannot be  maintained in adequate concentrations to be effective or lose efficacy quickly, not to mention this may be cost-prohibitive.  I've devised a failproof method to administer oral medications to fish consistently.

1. Obtain a 22 gauge, straight, non-flexible steel oral feeding needle (available here) and a 1 cc syringe.  I had the advantage of working in the veterinary field and had easy access but you can purchase these at medical surplus stores or online.  They are not cheap, but you will get many uses out of it.
2. Here is my setup: 

   

   Mine is a bulb-tip lacrimal cannula, but a gavage needle is more appropriate.

3. Draw the appropriate dose of medication into the syringe.  I will be posting how to determine dosing and appropriate medications soon. 

   

   0.25 cc Gel-Tek PX in 1 cc syringe

4.  It is a good idea to quarantine any fish being treated unless dealing with an infested tank.  In this case I am empirically deworming new wild-caught fish during a 1 week quarantine.  Even captive-bred fish should be dewormed before introduction to an established tank as intestinal parasites are rampant in the trade.
5. Trap the fish to be treated either with a net or by hand.  I find nets to be abrasive to the slime coat and I will ultimately be restraining the fish by hand so I try to hand-catch when possible. 
   
   

   

   L-204 pinned against the tank

6.  I try to keep the fish submerged as much as possible, but it will be necessary to turn it upside-down to insert the needle in the mouth.  Grip it firmly on either side of the skull to avoid damage to the esophogas via movement during gavage.  The stomach is located about even with the pectoral fins in most species, so try to gently slide the needle that far into the oral cavity.  Be careful to avoid accidental passage through the gills.

   

   Restraining the L-204

7. Once you're relatively sure the needle is inserted into the stomach, slowly depress the plunger to inject the medication.  Injecting too quickly can shock the fish or damage the stomach.  It is normal for the fish to act like it is 'coughing' during this process.  You would too if there was a tube sticking down your throat.

   

   Inserting the needle into the stomach via the oral cavity.

8. Replace the fish in water as soon as gavage is complete.  It may vomit up some of the medication especially if you injected in the esophagus but a majority will remain in the stomach.  Some fish may be extremely stressed by this process so it is imperitive to minimize handling time.  Ensure the tank they are placed in is highly aerated to minimize recovery time.
9. If deworming, expect to see feces passed between 30 minutes to 10 hours, depending on species.  White, stringy feces and worms are normal after deworming.  Most fish will be hungry after deworming; at least, all the fish I've treated have been ravenous within 2 hours, so be sure to provide food.
10. Repeat treatment as necessary.  Again, a chart of medications will be posted soon.