The 7 Most Deadly Mistakes A Fish Keeper Can Make

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Many mistakes can happen as an aquarium hobbyist - making mistakes is natural and helps us learn. But with fish, making such mistakes usually end up in fish death. 

But do not fear - we are here to help you easily avoid these mistakes or at least make as few as possible. 

Here are our top 7 deadly mistakes that even veteran aquarium hobbyists sometimes make!

  1. Adding Fish Before The Tank Is Ready

Let’s start from the beginning. You have started a new hobby or have upgraded to a bigger tank, which is both exciting and sometimes overwhelming! Trust me, I have been there, I set up my first tank, and the same day off I went to my local fish shop to buy some fish. After 1 week I noticed my fish getting sick and unfortunately they both died. 

This problem is down to not cycling the tank. This is the most essential part when setting up a new tank. Even if it is not your first tank but you have bought a new one, you still need to cycle it. This establishes the biological environment and removes any harmful toxins and excess waste. This can take any time from 3 - 6 weeks for the nitrogen cycle to happen. 

  1. Impulsive Buying & Compatibility

Getting your paycheck is exciting, and sometimes it is hard to control spending our hard-earned cash! For me, fish shops are like lolly shops, especially on weekends I used to spend hours in my local fish shop searching for beautiful fish to add to my aquarium. 

Impulsive buying and not researching before can cause many problems. You may buy fish that are not compatible with your other fish, plants, or corals. Or you may buy a fish that is small right now but will soon outgrow your tank or is greedy and will eat everything in sight. 

That is why before buying we always recommend speaking to the shop assistant and let them know what you already have at home, or do some research online. 

  1. Washing The Filter With Tap Water

This is a very common mistake with beginner aquarium hobbyists, admit it we have all been there at least once. 

Even though you may not be able to see it - your filter contains beneficial bacteria that convert harmful bacteria into less toxic properties.

Tap water contains chlorine and chloramine to keep us safe when drinking it, but it can be dangerous if your fish are exposed to such chemicals. 

To rinse your filter, use old tank water in a bucket/container. This means the beneficial bacteria are not removed and harmful chemicals will not enter your tank. 

  1. Replacing All The Water In The Tank When Performing A Water Change

It is important to do regular water changes, but a common mistake is replacing all the water inside the aquarium - this is a big mistake and likely to kill all your fish. 

By replacing all the water you will destroy the beneficial bacteria that has built up in the water. Removing this good bacteria will increase the ammonia levels in your tank, usually resulting in fish death. 

Always do a partial water change depending on the size of the tank you have and how much excess waste builds-up. The rule of thumb is around 15 - 20% - making sure to add a water conditioner and testing the water parameters before adding it to the tank.

  1. Overfeeding 

Overfeeding is the most common cause of fish death in the hobbyist world. Your fish can go 3 - 5 days without food, so if they are begging for more, they are just being greedy!

Overfeeding fish in aquariums leads to excess waste from uneaten food. This waste changes the chemical composition of the water and contributes to a spike in ammonia levels - which by now you know the outcome of!

Also, overfeeding can cause health problems for fish such as improper digestion, fatty liver, and fin rot. - All of which, you want to avoid.

You should be feeding them how much they can eat in 3-5 minutes. You can feed them one time, or spread it over 2 - 3 feedings per day. 

  1. Not Quarantining Fish Before Placing Them In The Aquarium

When you buy new fish it is very exciting! Even though you are probably told the fish is healthy and free from parasites by the fish shop, it is recommended you still quarantine them. 

There is nothing worse than placing new fish in your aquarium, and infecting your other residents, or even worse, killing them. Many parasites can not be seen with the naked eye and require microscopes to identify them. This means that they could be carrying something you do not know about. 

Before adding your fish place them in a separate tank (use mature tank water) and move some of the filter media into the tank. Leave the newly bought fish in a quarantine tank for a couple of weeks and monitor them for signs and symptoms of illness. If they do become sick you can treat them separately, and in the worst case, if they die, they would not have infected your community tank. 

When quarantining fish, only place one species from one batch into the tank at one time. If you will be adding more than one species, you should have more than one quarantine tank - this prevents cross-contamination. 

  1. Lack Of Patience

Becoming a fish hobbyist requires patience. Just like gardening, plants in your aquarium also require time to grow, and your fish need time to mature to gain full colouration. If you are keeping corals, these take even longer to grow, so you need to be even more patient. 

Most of us work during the week, and the weekend is our time to relax and focus on what we enjoy - for us it is fish keeping! This usually means searching for something new we can add to our aquarium. Adding too many fish at once leads to overstocking. 

Imagine in one day you have new housemates moving in all at once, which would be stressful right? Your fish feel the same. When adding new fish this should be done gradually, and not forgetting the quarantining process.

If you are inpatient, maybe keeping fish is not the right hobby for you. There is nothing wrong with visiting the fish shop to have a look, there is no need to take out your wallet, just wait until the time is right - for example, you may need to buy a larger tank if you do want to increase your stock.

Finishing Notes

Remember mistakes are likely to happen, but after reading this you should be more comfortable and can prevent them from happening. 

Don’t forget to join our “Help & Advice” support group on Facebook. We offer FREE support from a qualified marine biologist!

Thank you for reading. We hope to see you soon, have a ‘fintastic’ day!

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