Hurricanes and Nimbochromis venustus cichlids

Hurricanes and Nimbochromis venustus cichlids
© Copyright Susan L. Marsh, All Rights Reserved

     Up until Hurricane Frances struck my area, I had a 10 gallon aquarium with happy juvenile cichlids in it. There were eight 1.5” juveniles, including four Nimbochromis venustus. The venustus are the focus of this short article.
My usual routine was simple. I changed some water in my tanks on a weekly basis (sometimes more often). Twenty to twenty five percent was the norm for the water changes. I used straight well water, and had been doing this successfully with this particular group of fish for a couple of months. A few days after doing the water change, I would rinse out half of the hang-on power filter pad. I also had a small corner filter in the tank for extra filtration, air stone powered. I continued this routine up until Hurricane Frances came.
To prepare for the hurricane, I had extra buckets of water set aside in case of a tank breaking and fish needing temporary homes. I had a battery powered pump to run the corner filter for when (not if!) the power went out. I fed a little less food in the three days before the hurricane to prepare for the filtration being reduced. I had a flashlight by the tank to check on the fish during the hurricane and to use as a light afterwards. I was prepared for anything, or so I thought.
As it turns out, I was not prepared for the reaction of my venustus’ to the hurricane. As Hurricane Frances approached, they went crazy! They started zooming around the tank like something was trying to eat them, causing the other four fish to cower in their caves. They were not attacking each other or the other fish, just swimming frantically around. I checked the temperature, ammonia levels, nitrate, nitrite-all to no avail. Nothing was out of the ordinary. I changed ten percent of the water just in case-no change. We still had full power at this time, so they still had their normal lighting. I watched helplessly as they zoomed around the tank, battering themselves into the sides. I tried turning off the lights and covering the tank with a towel to calm them down. They then started throwing themselves out of the tank against the lights. I took the light hood off and covered the top of the tank with another towel to try and reduce the impact. Over a period of several hours, I listened to them frantically leaping against the towel, splashing back down into the tank. At one point I netted some out and put them in a different tank with the same result. I gave up and put them back into their original tank so at least they would know the territory. All four fish died within 24 hours of Hurricane Frances approaching the coast.
Looking back, I have tried to figure out what went wrong. Was it water chemistry? Everything was the same, and none of the other fish were distressed. The lighting? No, this started happening before the power went out. The only conclusion I could draw was that this behavior was caused by the change in atmospheric pressure. Perhaps it affected their nervous systems and drove them “crazy”, perhaps it affected their swim bladders and they felt they could not stay afloat. The pressure was the only parameter different from one day to the next. Since Frances came ashore only a few miles from my house, the pressure change was very pronounced. Unfortunately, that is also the one variable that I could no prepare for. I am still at a loss as to what I could have done to prevent their deaths. I eventually replaced my beloved venustus, this time obtaining fish from a different source in hopes that it was a genetic fault that made them overly sensitive to the pressure changes. After speaking with others in the aquatic hobby and industry, my fish were not the only ones that exhibited strange behaviors (including trying to jump out of tanks) due to the hurricanes. And like me, no one has any idea how to prevent deaths from fish going crazy. This just illustrates that sometimes, you cannot prepare for nor prevent everything from happening with Mother Nature.

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