Reasons Why Marine Fish Die in Aquariums

Aquariums offer a window into the enchanting underwater world, showcasing the vibrant and elusive life that thrives beneath the waves. However, maintaining a healthy marine aquarium is a delicate balance of science and art, with various factors influencing the fragile creatures’ well-being. In the article, we shed light on the common pitfalls aquarium enthusiasts encounter, which inadvertently lead to the loss of marine life. This comprehensive guide not only explores the myriad reasons contributing to the demise of your beloved fish but also provides invaluable insights and preventative measures to foster a thriving aquatic environment. Delve into the essentials of marine aquarium maintenance and safeguard your underwater inhabitants against the silent killers lurking in the tank. Your journey towards a resilient and flourishing marine aquarium begins here.

Reasons Why Marine Fish Die in Aquariums

1.   Starvation and Diet

New arrivals have a greater chance of not eating hand-fed foods for 2 reasons. First, many fish have not been properly fed since they were caught until you put them in the tank. The collectors normally don’t feed what they catch because it will make the fish poop in the shipping bag. Poop in the shipping bag equals ammonia in the water, which means less O2 in the bag and burnt fins and gills.

For the most part, sick fish don’t eat. Also, many aquarists don’t offer the fish the food they normally eat. Mandarinfish are a perfect example of this. Mandarinfish normally eat copepods and amphipods in the wild. They will not take any interest in that flake food you try to tempt them. There are methods for getting finicky fish to eat, but that is a topic for another article. When fish haven’t eaten for a while, they tend to lose their appetite, and it may not be easy to get them to start eating again, even if a desirable food is presented.

2.   Improper Acclimation

Many aquarists do not acclimate their fish properly. They might adapt them to the temperature difference between the bag water and the aquarium water, but they don’t take the time to adapt them to the difference in pH. Some fish (and many invertebrates) are more sensitive to pH change than others. Taking the extra time to adjust the pH slowly will eliminate many critter deaths in an aquarium.

3.   Parasite and Disease

Many fish (particularly surgeonfish) carry parasites (i.e. oodinium and cryptocaryon) hidden in their bodies. They may not be apparent when you receive them, but stress from capture and shipping can cause an outbreak in your tank shortly after you put them in. Fortunately, most fish diseases are curable if caught in their early stages and treated properly. Before placing them in your main tank, quarantine tanks are highly recommended for new marine fish arrivals. The parasites, in and of themselves, are not the actual “cause of death.” The actual cause of death is usually suffocation resulting from the mucus that the fish produces in the gills due to the parasite boring into the gills. Quite often, even if the parasites are killed, the resulting lesions become infected, causing death.

4.   Incompatibility

No matter how much you might wish otherwise, a Volitan lionfish will eat any fish it can get in its mouth. That might seem like an extreme example, but many other fish species will not get along with certain other (or even some of their own) species. Using a good compatibility chart to see what probably won’t work together in your tank before you buy a new addition will save you a lot of time and money.

5.   Poor Water Quality

To survive, fish require a stable environment within certain parameters. These parameters include proper salinity level, pH, low to no ammonia, and nitrates. Poor water quality contributes to immunological weakness, infections, and health. A fragile fish makes a good target for other fish to pick on. Proper water quality can be maintained by several means: partial water changes, proper filtration, adding trace minerals, regularly balancing the pH, and not overstocking the aquarium. Understandably, beginning aquarists lose more fish than experienced aquarium keepers. There is a lot to know, particularly with saltwater aquariums, and the learning curve is pretty steep.

6.    Capture and Shipping methods

It should be mentioned here that many problems in hobby (and others) marine aquariums result from poor capture and shipping procedures. When a fish arrives in your LFSs and gets into their display tank, it has gone through many hands and been in several shipping bags. Normally, the collector catches the fish, takes it to a shipper, who puts it in a bag and ships it to a trans-shipper or wholesaler, who puts it in his system, then re-bags it and ships it to your LFS. Knowing how to identify signs of stress, disease, infection, etc.. Buying a new specimen will help avoid those new arrival deaths we often hear about.​