Funny Fish picture

Why did my fish die suddenly?

For marine aquarists, nothing is as disappointing as losing a beautiful fish. We can understand a loss if the fish was unsuccessfully battling a marine Ich outbreak. The symptoms are visible and unfortunately we can witness the fish struggling to recover over a week or longer. Sometimes incompatible fish fight, usually picking on a fish until it is ragged and weak. Try catching the bully or the victim in a reef tank. It is nearly impossible! Fortunately these events are relatively rare. There is no joy in relating these stories, but let me bring up one more example. This one causes a lot of confusion, worry and sometimes misplaced blame. It is when a perfectly healthy marine fish suddenly dies, for no apparent reason.

Scenario One: The New Fish Dies Suddenly

You love to stop in your local fish shop to check out the newest saltwater fish. If you are really hard-core, you are there when they unpack the Styrofoam fish boxes. You want to see the new stuff right away.  Ever have a new fish, everything is going great. Then, after a couple of weeks, the fish is dead. No symptoms. Just dead. All the other fish in the aquarium are perfectly healthy. Why?

 Scenario Two: An Established Fish Dies When a New Fish Added

This one drives saltwater aquarists crazy. Imagine an established reef tank or even a saltwater fish aquarium, complete with an established population of fish. All is well. One new fish is added to the aquarium. The new fish acclimates quickly and looks beautiful. Then, suddenly, one of the established “old timers” suddenly dies. What the! This makes no sense. No other fish show signs of stress or disease. One might expect the new fish to be the weakest specimen, but not one of the well-established fish.

 Funny Fish picture

Who to Blame For Fish Loss?

Out of frustration it is easy to blame the other guy for this unexpected loss. The marine fish importer wonders if the fish was caught using cyanide. Maybe the fish was treated roughly. Perhaps the shipment was delayed at the airport. The fish store owner wonders if his supplier had poor quality fish. Did one of the store employees mishandle the acclimation process? The aquarist may blame the fish shop for selling “bad fish.” Many times aquarists feel so awful they blame themselves for not caring for their fish correctly.  Was it the marine salt? They may second guess their test kits. “Maybe something is wrong with my water?”

 What Really Happened?

Just like sudden death in the real world, it can happen in the fish world. If you’re sure you’re doing things right, don’t beat yourself up. Sometimes it just happens.

 What to Do If It Happens To You 

While many aquarists never experience this sudden loss, if it does happen there is no need to panic. Remove the dead fish as soon as you can. Discard by disposing the fish in a plastic bag, placed in the garbage can. If trash day is a while away, you can freeze the fish if that won’t cause your spouse or other loved ones to divorce you. Do not flush it, if you can avoid it. You could clog up the plumbing (guilty).

There is no need to “bomb” the aquarium with medications, especially if it truly was a one-off sudden death.

If the fish decayed, test the water for ammonia and nitrite. Make a water change if the tests are positive. Overall the rest of your marine fish will be perfectly fine. Breathe easy. Contemplate the loss. See if there is anything to be learned… and if not…move on. It’s not your fault. You may think you need a reason for closure, but sometimes we just don’t know what happened and that’s ok.

Carry on and good fishkeeping!






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