Why do my fish keep dying?

Why do my fish keep dying?

Mistakes beginner fishkeepers make

two dead goldfish neglected in an aquarium

two dead goldfish neglected in an aquarium

There can be several reasons for the death of your fish; however for beginners the main reason is new tank syndrome. This is a situation where you have bought new fish and placed them in a newly set up aquarium. Your fish start dying and you are unable to explain the cause. This syndrome is usually experienced by new fish owners who have yet to master keeping fish safe, healthy and alive. Here are some things that you should look out for and avoid to explain and prevent new tank deaths

  • Uncycled aquarium & filter
  • Water chemistry problems
  • Diseases
  • Poor diet and overfeeding
  • Over population
  • Wrong type of fish
  • Buying sick fish

Uncycled aquarium & filter

dead catfish on the tank floor

dead catfish on the tank floor

Most fish owners will be buying their new pets along with new equipment, such as an aquarium and a filter. They will fill the aquarium with water and then put in the fish and they will think that the work is done. This is a common error by most new fish owners. Even before you introduce your desired fish population, you need to create a nitrifying bacteria bed in your aquarium and filter.

Take note that the same way human bodies have good bacteria that can protect them from harm, so does the aquarium. An aquarium and especially the filter must have good bacteria that can protect them from risks to their health. The bacteria work by neutralizing or converting toxins that are produced by the fish’s droppings and urine such as ammonia and nitrites.

Without good bacteria, these toxins build up in the aquarium. When they reach dangerous levels, the fish will absorb these toxins and cause them to become ill. Since it is often difficult to detect if a fish is sick, new fish owners will only discover it when it is too late and the fish are dead or about to die.

It takes time for the healthy bacteria in the filter to build up, between 4-6 weeks before a healthy population of bacteria develops in the filter capable of fully removing fish waste products. So, what do you do in the mean time? You have to do daily partial water changes to dilute these toxins. Perhaps, remove 5% of the water and top up with (chlorine free) fresh water.

dead fish on the tank floor that needs removing asap

dead fish on the tank floor that needs removing asap

This explains a common pattern to newly bought fish that will be fine for up to a week or longer. Then something seems to change and the fish start getting ill. Finally they start to die. And, the few fish that survive start to get better and if all is well the survivors live a long time.

This is all explained by the cycling of the filter and the fish waste product. When the fish first enter a new aquarium with fresh water there is no waste matter in the water. As the fish start to poop and urinate in the water this waste starts to build up. This poisons the fish. Slowly the bacteria in the filter build up and digest this waste cleaning the water, but this takes weeks to establish.

Water chemistry problems

Fish require a delicate balance in the chemicals in the water. Clear water does not necessarily mean an ideal environment for the fish. Ammonia, nitrites and nitrates are some of the chemicals, which when uncontrolled, can cause significant harm to your fish that will eventually lead to death. These toxins are from the waste your fish produce. These are harmful toxins that should be neutralized or kept at a minimum during the course of your taking care of the fish.

Cycling explained in full here

When looking after fish as pets you are not necessarily taking care of the actual fish themselves but rather of the water quality instead. Measuring devices and kits are available to keep a check on the various chemical parameters of the water of your fish tank. You must also have keen observation, noting changes such as the tinge of the water, any discoloration of the gravel in the aquarium or the behaviour of your fish. However, as a beginner, if you rely solely on observation, the toxic levels will already be too high to before you understand that something is wrong. At this point any chance for survival of your fish is slim.

Tap water usually contains chlorine which is lethal to your fish. To remove it leave the water standing for 1-2 days before adding to your aquarium. Alternatively, use dechlorinating medication that removes chlorine immediately from tap water.
Check the ph and hardness. Ph between 6.6 – 7.6 is okay for most fish. Test the hardness level. A moderate level of hardness is ideal for most beginner fish.
Diseases

Don’t buy sick fish! Beginners often buy fish that have illnesses from the pet shop. This is easier said than done. Check the pet shop aquarium if there are any sick or dead fish in there. Check if there are any spots on the fish or markings or fungus like patches. Make sure the fish are active and swim towards food. Don’t buy fish that are sulking or have clamped fins (ie fins held close to the body). Check the fish has bright colouration.

Another cause for fish death is because of disease. As the water quality becomes poorer from elevated levels of toxins, the fish health also becomes poorer with it. When the fish become weaker, they are more vulnerable to disease. A healthy fish will normally be able to resist these illnesses but a weakened fish will succumb to them.

Some examples of these diseases are bacterial infections, fungal infections, internal parasites in the fish’s body, dropsy and other opportunistic diseases. Most new fish owners will attempt to cure these diseases by adding antibiotics, anti-parasitic or anti-bacterial medicine into the water. However, without treating the underlying cause of the disease, which is the toxicity from waste matter, there will still be fatalities, despite the medication. Experienced fish owners are able to nurse a fish back to health where a beginner may or may not succeed.

Poor diet and overfeeding

Most new owners will enjoy feeding their fish. Who wouldn’t enjoy seeing their fish swim towards the food and follow the trail wherever you sprinkle the food? It is also fun to see some fish diving towards a food pellet that sinks towards the bottom of the aquarium. Ironically, feeding your fish or rather overfeeding is also one of the main causes of fish death.

Fish should be fed once a or twice day, with the fish eating everything within 5 minutes. But most new owners will feed their fish every chance they get. On top of this over feeding, other members of the family may also be feeding the fish on their own without the owner’s knowledge. Fish food that is uneaten, such as food left floating on the surface of the water or sitting on the aquarium bed will rot and pollute your aquarium, leading to the same problems as fish waste. Rotting food in the aquarium is the second biggest cause of fish deaths after new tank syndrome.

Over population

Another cause of death for fish is the population itself. Despite the care you make on making a balance in the water chemistry, proper feeding schedule and best equipment you can provide, your fish may still die because there are just too many fish in too small an aquarium. But problems may also arise if you have the wrong combination of fish species.

There isn’t a strict rule on the ideal number of fish for a certain size of aquarium. More experienced fish owners recommend a ratio of 1 inch of fish for every 1 gallon of water. Take note that the 1 inch is meant to be measured on each fish’s eventual adult size. The more fish there are, the greater the chance for oxygen deficiency, self pollution and diseases to spread.

The wrong combination of fish can also lead to stress and deaths. If you put together an aggressive fish with a more passive or smaller fish, the passive fish may be bullied. In their natural environment, a passive fish would be able to escape the aggressive fish, but in an aquarium they have no chance for escape. The constant stress will cause death.

Wrong type of fish

Finally, the beginner may have bought a difficult to care for species of fish. Difficult fish may need special water requirements, special dietary needs or some other type of specialised care. You must always ask the pet shop owner if the fish you are buying are beginner community fish to avoid such problems. Only buy more difficult fish when you have more experience.

You should buy popular starter fish such as gold fish, tetras, platies, swordtails and bettas. These are colorful, active and most importantly easy to care for. Avoid buying difficult fish such as saltwater fish.

Recommended compatible fish groups here

Conclusion

Once you have mastered the two main causes of fish death which is new tank syndrome and rotting uneaten food in the aquarium you will have a good chance of keeping your fish alive long term. And, if you follow all the above advice you should hardly ever see a fish death in your tanks. If you follow all this advice, not only will your fish stop dying but you will see your fish in full glowing health.

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