Keeping fish in an aquarium is fun, and it is one of the most popular hobbies among pet keepers around the world. Sadly, the truth is that on the average fish only live for three weeks after leaving the shops. What can cause the fish die so quickly?
In at least over 90% cases, fish die early because of the following beginners’ mistakes:
1. Fish Died to Untreated Tap Water
You must know that fish can’t survive in untreated tap water. Tap water contains chlorine and chloramines. Water companies use them to disinfect. Both chlorine and chloramine can and will kill the fish. While Chlorine can evaporate slowly if you let the tap water sit for a few days, chloramine is a different story, and it is there to stay.
The solution to this problem is straightforward. Buy a bottle of aquarium water conditioner. Years ago when I was a kid, people used solid crystal like water conditioner. Nowadays, most water conditioners are in liquid form.
While they are all good and work just fine for their primary purpose, I recommend Prime for new tanks. It can also detoxify ammonia and nitrite for up to 48 hours. It can come in handy for a new tank.
2. Fish Died to Shock From Sudden Changes in Water Parameters
Do Not Skip New Fish Acclimation
Most fish can adapt to a range of water chemistry (PH, hardness, etc.) and water temperature without a problem if given time. However, many new fish keepers do not know this. They will just “dump” newly bought fish into their fish tanks immediately. The water in the tank obviously has different chemical makeup and temperature compared with the water in the plastic bag that came with the fish. Unlike the human being, fish are cold blood animal, and they can’t regulate their body temperature as we do. A sudden change of water temperature can “shock” the fish and even cause them to die! The water PH and hardness are also critical; the sudden drastic change in either of them can cause fish to die.
Solution: You must acclimate the fish. Before opening the plastic bag, you should put the bag into the fish tank water. Let it sit there for at least 20 minutes for the temperature of the water in the plastic bag to become the same as the water in the tank. Many novice fish keepers do that after listening to the sellers at the fish stores, however, what they miss is the next step.
Now the water temperature is the same after the fish bag has been sitting in the fish tank water for over 20 minutes, but the water chemistry such as PH and hardness are still different! What now?
I usually do the following. Use a plastic fish container, and dump the fish & water from the plastic bag into the container. There is no need to transfer all the water if the container is not big enough. Then get rid of some water (around 25%) from the container (throw that water away, do not put it into the fish tank), and refill the container with water from the tank.
Wait for 10~15 minutes, then get rid of some more water from the container, and refill it with the water from the fish tank. Repeat that process every 10~15 minutes with no more than 25~30% of water replaced each time. Until the water in the container is almost all from the fish tank instead of the pet shop water from the plastic bag. In this way, the fish have the time to get used to the new water parameters slowly. The whole acclimating process usually takes me about 1.5~2 hours. For more sensitive fish, it can take 2~3 hours before I feel safe to add the fish to the tank.
Aquarium Heater is mandatory for tropical fish
We based the above scenario on the assumption that you have an aquarium heater if the fish you keep are tropical. It does not matter how slowly you try to make the fish adapt the new temperature, tropical fish (such as betta) will die if there is no heater to keep the water at the tropical water temperature which is usually around mid 72~80F+.
Most aquarium fish sold at the shops are tropical. If you are looking for a heater, I would recommend EHEIM Jager Heater. I use a 50w heater in a 40-gallon tank, and the temperature is very stable since I have good water flow around it.
Shock from water changes
Fish tank maintenance might also cause shock to the fish if the fish owner did it wrong. Some new fish owners would do 100% water change, or even take out the fish. It is a bad idea. A lot of fish died because of this practice. If you change all of the water, there has to be a significant change in the water parameters. It is exactly what we must avoid. Typical aquarium maintenance should have a (partial) water change of no more than 30~50% each time. The water should come from the same source every time. It is also critical to make sure the new water has similar water temperature compare to the water in the fish tank. You can say every water change is also a form of fish acclimation. Without doing it correctly, fish die quite fast.
3. Fish Died from Ammonia and Nitrite Poisoning
Ammonia and nitrite poisoning is a more complicated problem. First, you MUST have an aquarium filtration system running 24/7 if you plan to have fish. Without a filter, no fish will be alive for long. That is certain, and there is no way to get around it. Second, you must understand Aquarium Nitrogen Cycle.
Now let us talk about why we need a filter and why there are ammonia and nitrite poisoning.
Aquarium Nitrogen Cycle
Fish produce ammonia as a natural waste. Ammonia is toxic, and it will harm the fish. In a natural environment such as a lake or a river, there is so much water, and it removes ammonia quickly, but in a closed system such as in a fish tank, ammonia builds up and become more and more concentrated! It burns the fish’s gills, and it can kill the fish when the concentration is too high or exposed to low concentration for too long. Usually, in two to three weeks, the level of ammonia concentration in a fish tank will be sufficient to kill the fish.
Now what? How do we remove the ammonia from an aquarium?
The answer is you do not need to remove it physically. In a well-established aquarium, there are naturally occurring bacteria that feed on ammonia as food. Most of these bacteria live on the filter media where there are lots of surface areas. (These bacteria only colonize in the surface areas)! The ammonia feeding bacteria will convert ammonia to nitrite. However, nitrite is even more toxic than ammonia!
Now what? There is a different type of bacteria feeding on nitrite, and convert it into a much less harmful form – nitrate. The second species of bacteria also colonizes the surface areas in the fish tank, and just like the first type of bacteria, they mostly stay on the filter media because that is where the most surface areas are in a fish tank.
Nitrate is entirely harmless to the fish until there is exceptionally high concentration. Ammonia and nitrite must be kept at 0 at all times if you want your fish to live.
However, it takes up to 6~8 weeks for these two types of bacteria to grow into sufficient number to keep the ammonia and nitrite at 0, if…and only if there is a constant source of ammonia. By having fish in the aquarium, there is a continuous source of ammonia, but the fish will usually die before the 6~8 weeks is up!
What did I say? You will never have remotely close to enough bacteria to feed on ammonia and nitrite if there is no fish (source of ammonia). But your fish will also die if you add it to the fish tank before there are enough bacteria. It makes no sense, does it? It sure sounds like nobody can keep fish alive at all if the fish tank is newly set up.
There is a solution to it. You should not add any fish to a new aquarium until you do a fishless cycle!
To test your water chemistry for ammonia, nitrite, nitrate, and PH, you need a liquid water test kit. (Paper strip kits are not accurate at all.)
I use API freshwater master kit. It is far more accurate than paper strip test kits. And it is, in fact, more cost-effective due to you can use it for over 100 times.
For saltwater aquariums, you need a different test kit called API Saltwater master kit.
Aquarium Filtration System
As mentioned earlier, the aquarium nitrogen cycle requires a filtration system running 24/7. Every home aquarium must have a good filter, or fish will die.
If you are looking for advice on a filter, I recommend AquaClear power filter if you are on a budget. They are very reliable.
For large fish tanks, I recommend canister filters. They are more efficient at biological filtration, and they make no noise at all, but they cost more. I use an EHEIM Classic 2213 for my 40-gallon tank, and I am pleased with it. It is a high-quality German brand.
4. Fish die to Overfeed
Overfeeding is a source of many problems. Fish do not need to eat remotely as much food as humans. They have no need to burn calories to keep a constant body temperature. Many new fish hobbyists have no idea. They keep feeding fish large amount of food multiple times a day. Too much food can kill the fish directly with the digestive problem. Uneaten fish food will rot and pollute the water. It will cause ammonia and nitrite spike, which will indirectly kill the fish.
The ideal feeding routine for aquarium fish should be once a day, with no more food than the fish can finish within a minute. Uneaten food must be removed as soon as possible. Stop overfeeding fish can also solve a lot of the aquarium problems such as pest snail infestation and algae overgrowth.
5. Fish die of Diseases and Parasites
There is also the fish disease problem. A lot of fish farms, wholesale warehouses, fish shops, have poorly managed fish tanks. Many contagious fish diseases and parasites run rampage. Fish ick (also called fish white spot disease); fish mouth rot (also called fish mouth fungus), just to name a few. They are often deadly if not treated immediately, and they kill a lot of fish in the hobby.
Because most fish shops have the centralized filtration system, a single infected fish can spread the disease and parasites to every fish tank in the system. The likelihood of getting a fish with a disease is extremely high every time we buy new fish. Purchase fish from a reputable source is a good idea to ensure you get high-quality fish to begin with. Purchase fish from a poor source is asking for trouble. It is also when you need a quarantine tank to separate new fish from the fish you already have. All new fish should be in a quarantine tank for at least 2~3 weeks for observation. Or you might risk losing the whole tank of fish.
Some fish hobbyists use a mild general purpose fish medication such as Paraguard in the quarantine tank for all newly arrived fish whether or not they show any sign of a problem. It is one good way to minimize the chance of new fish dying.
Conclusion: Most aquarium fish only live a short, and miserable life, because most people did not get the right guidance before they started. Let us hope more novice fish keepers do things right, so there will be less fish die in home aquariums.