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Common Care Mistakes from New Fish Owners

Updated: Apr 10, 2020

It’s often assumed that keeping fish is easy. They’re the option many people go to when they *technically* get their kids a pet. Because of this, many people don’t consider that setting up fish might be a bit of a chore. Sure you don’t have to teach them how to sit, take them for walks, potty train them and things you’d usually have to do with pets, but the initial set up for fish is more than you’d usually have to do with other pets, and it’s easy to make some mistakes along the way. So, from feeding your fish the wrong type of food, to not letting bacteria build up before you add fish, here’s the top 10 mistakes new fish owners make and how you can avoid them!

The first common issue is overfeeding your fish

Feeding too much leads to eating too much, which leads to pooping too much. This then leads to a water quality issue as your filter can’t clean the water efficiently enough and can make your fish sick if you don’t perform regular water changes. The alternative is that your fish don't eat all of the food, the food decays and releases nitrites/nitrates which are toxic to your fish. Aim to feed your fish an amount of food that they can consume in around 3 minutes. If you want to feed them small amounts bit by bit for the three minutes, then you can do this until you know how much a portion should be.

An important tool to have at your disposal is a water testing kit. Your aquarium could look pristine to the human eye, but it could contain large amounts of things such as nitrates in it and we would only notice when the fish become sick. The only testing kits we recommend are all by API. There's the Master Test Kit, which you'll probably only need to purchase once because of how many tanks it can test, and there are packs of 5 in 1 Test strips. These strips do the job and are cheaper as a short term investment.

If you notice that after you’ve fed your fish there’s flakes on the gravel for a while after then you’re feeding them too much. To feed your fish flake food, take a small pinch of food from the container, don’t shake the food out as this is a very easy way to overfeed. If you’ve put too much food in, use a net to take some back out and dispose of it.

Most fish are opportunistic feeders and search for food all day long. Grazing herbivorous and young fish (like guppies or small angelfish) may need two small feedings per day and may benefit from having plants to nibble. Some fish are omnivorous and require more protein, like African Cichlids or, in saltwater aquariums, triggerfish. These fish can eat once per day and enjoy a more substantial meal of freeze dried or frozen worms or shrimp. Include scavengers like snails and crabs in your tank to balance out the community and clean up uneaten food.

The Nerite Snail is an amazing option here, as they don't breed in tanks and they'll eat up all of the leftovers and the algae. You can learn more about Nerite snails in our guide on The Best Algae Eaters for Freshwater Aquariums.

New Tank Syndrome

“New tank syndrome” comes from a tank that lacks a sufficient population of bacteria necessary to process the nitrogen compounds that come from fish waste. Building up bacteria in your tank water starts by adding a few hardy, inexpensive fish (like tetras or platys to a freshwater aquarium or damsels to a saltwater aquarium) to your fish tank. After adding the starter fish, allow time for the nitrogen cycle to proceed. Some experts recommend adding sand or gravel from an established tank to move the process forward.

There are also a variety of additives that can help you establish the bacteria and cycle the water more quickly. Monitoring the nitrogen compounds with a chemical testing kit (Such as the API kits we've discussed) will reveal how the tank is cycling and indicate when you can begin slowly adding more fish. Most aquarium stores will gladly test water samples and offer guidance about the best practices with your tank.

Mixing and mismatching your fish species

If you know any fish owners then you’ll know that fish have personalities. This can mostly be categorised by the species of the fish, and some fish shouldn’t be put with others. Before you add a new species of fish to your tank, check that they’re compatible with the other species already in the tank. Some fish can be bullies and aggressive towards other fish and you want to keep this to a minimum, as stress is a killer in fish.

If you really fancy an aggressive type of fish, then stick to only keeping those species of fish in that tank. One exception though, is the Betta fish. Nicknamed the Siamese Fighting fish for good reason, two males of this species will fight to the death. Even a male and a female will, and should only be kept together for breeding purposes under strict observations.

Mixing aggressive fish with passive fish can lead to bullying. Fish that are too frightened to come out of hiding during feeding time will eventually starve to death. Avoid making impulsive purchases of fish and plan your tank selections in advance with research.

Overcrowding Your Tank

Planning for your fish population is an important first step. The rule to keep in mind is one gallon of water per inch of fish, though bear in mind that aggressive fish require more lateral swimming space. If you select aggressive fish, double the size of your fish in calculating the number of gallons of water per fish needed for swimming space.

Ensure that your sums are for the adult or fully grown length of the fish, for example goldfish start out small but can grow to be an entire foot long - so when they’re young it’ll seem like they have a lot of space, but space will quickly run out as they grow. Also bear in mind that ornaments and rock formations will also take up space - If your 50L tank has 2Ls of rocks in, you have a 48L tank for fish.

Taking a holiday without backup plans

Before you head off on holiday, do a water change and clean your tank the day before. This will lower the chance of any issues arising. If you don’t have anyone who can come and feed your fish when they need to be fed, then consider investing in an automatic fish feeder such as this one. Another option is slow dissolving fish food cakes which will slowly let out food over time.

Make it as easy as possible for a sitter to give the correct amount of food by setting out portions in a weekly pill organizer. Explain how to check the temperature of the tank and make an adjustment if needed. Leave written instructions for how to deal with tank issues such as water evaporation, death of a fish or cloudy water conditions as well as contact information of a trusted aquarium store professional or fellow hobbyist.

Not Understanding Temperature Control

Smaller tanks are subject to faster temperature swings than larger tanks because they have less water that needs to be heated. This works in the same way that chemical imbalances are easier to handle in larger tanks too. Use a simple temperature-sensitive sticker to help quickly monitor the heat. Fish and invertebrates are sensitive to shifts in temperature, so make it a point to check the heater or chiller regularly. Avoid placing the tank near a draft or a sunny window and monitor the temperature to stay between 22 and 25 degrees celsius or 72 and 75 degrees Fahrenheit.

Keep in mind that some species require slightly lower or higher temperatures. For example, koi and their popular cousins, the goldfish, are best kept at temperatures between 50 and 70 degrees Fahrenheit, while freshwater angelfish come from warmer waters and prefer temperatures between 78 and 82 degrees Fahrenheit.

Overlooking Disease

Paying close attention to the appearance and habits of your fish can help you catch illness early. Early detection is the best way to prevent disease from spreading to other members of your tank. Adding new fish is often the source of a disease that they bring from their usually overcrowded pet shop tank and when fish are transferred to a new environment, the stress can weaken their immune system making the fish susceptible to infection.

Keeping a quarantine tank for newcomers to occupy before release into your main tank is an important step in guarding against the spread of disease. Most fish hobbyists advise that new fish should be quarantined for 21 to 28 days.

Check out our guide on how to spot fish disease here: Common Care Mistakes in First Time Fish Owners

Fish should appear hardy, have clear skin and eat readily before transferring to your main tank. The quarantine tank also serves as a hospital when you have a fish that looks ill. If possible, transfer the fish to the quarantine tank and seek medical advice for the best treatment protocol.

Neglecting Your Tank

Forgetting to feed your fish, not keeping up with the maintenance of your tank and not monitoring its water quality will limit the lifespan of your aquarium. Successful fish hobbyists routinely maintain the needs of the tank on a schedule.

If marking the calendar to note when it’s time to change the filter or setting an alarm to feed the fish isn’t your style, consider some automatic feeders and water quality probes that might help keep you on track. There are even water quality monitoring devices that wirelessly connect to your home computer system to alert you of any changes. We recommend setting up a specific maintenance schedule that can help keep you on track.

If you fear your interest in the hobby is waning, take a trip to a public aquarium or even your local fish store to get some inspiration.

Being Impatient with Tank Maintenance

“Slow and steady wins the race.” This quote applies to tortoises racing overconfident hares as well as to fish hobbyists. Having a fully-stocked show tank does not happen overnight. Planning and researching the equipment, monitoring the water quality and purchasing compatible inhabitants are essential steps to success.

Taking the time to build up a show tank will help you avoid common mistakes and induct you into a long-lasting hobby that millions of people enjoy.

Using “People” Water

The water you use for brushing your teeth and bathing is treated with chlorine and can be toxic to your fish. Treat water with chlorine-removing additives such as API's Master Test Kit or 5 in 1 Test strips , following the directions for use.

Refrain from using any soaps on your aquarium equipment. Hot water and small measures of bleach or vinegar carefully rinsed away should be sufficient. Store bottles of treated water to use for replenishing the tank after evaporation. Keep up with water changes between weekly or every two or three weeks depending on the size of your tank and how passively the tank cleans itself. If you're not sure if your tank cleans passively, then it probably doesn't and you should change it weekly just to make sure. For info on how to set up a minimal maintenance aquarium, see the list of links below! Thanks for reading.

Thanks for checking out this Fish Article! Here's a list of our other popular articles:

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Common Care Mistakes in First Time Fish Owners

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The Minimal Maintenance Aquarium Set Up Guide

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The Best Algae Eaters for Freshwater Tanks

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