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Preparing For The Introduction Of Your New Fish


General Advice



It’s a very exciting time adding a fish tank to the family home or office. The team at will help you set up your fish and become a successful fish keeper.

Here are a few of the things you will need to get started...

  • Fish aquarium - getting the right size for your requirements is the first step
    A lot of aquariums come with fish tank light fixtures and fish tank filters included. These are generally the best way to go if you are just getting started

  • Fish tank gravel, ornaments, fish tank backgrounds and plastic plant decorations

  • Gravel syphons

  • Fish tank plant fertilizers and substrates

  • Plants

  • Filter and light hood (if your tank doesn't already come with one)

  • Water conditioner

  • Bacterial additives to get the biological cycle up and running

  • Fish tank test kit

  • Fish tank net

  • Cleaning kit - sponge, fish tank scrapers, extendable scrubber

  • Timer and multi-plug to plug everything in with

  • Fish Food - a variety is best to ensure a good balanced diet for your fish
    Optional - but highly recommended:

  • UV Sterilizer

  • Co2 Diffuser

Positioning your tank in the right place

Try to place your fish tank in a place that has a constant temperature, and one that is not in direct sunlight. This will help you to maintain a consistent environment.

Setting up your aquarium

  • Keeping in mind that 1 litre of water weighs 1kg it’s worth taking time to properly set up your aquarium. If you have a 50 litre tank it is going to weigh 50kgs, so it's essential to double check the stand and make sure that it is going to be strong enough. Larger aquariums can weigh over 200kg so also check the floor is strong enough and level as any discrepancies can cause a twist in your tank.
  • Once placed in the correct position, wash out the gravel thoroughly, you don’t want to have any dust in the gravel transferred into your aquarium. Also place all of your fish tank ornaments and rocks to make sure you are happy with the look of your aquarium.
  • Place all of your accessories like aquarium heaters, UV Sterilizers and aquarium thermometers in the correct place - this is much easier to do without water in the tank. DON’T TURN THEM ON until you have water in the tank.
  • Place the aquarium gravel along with any substrates into the fish tank, then pour water into the tank. Pour directly onto the back of a flat plate to make sure that the pouring the water into the tank does not disrupt the gravel.
  • Once the tank is full you can get the aquarium filter going and turn on all of the tanks, lights etc.
    At this stage you can start adding in water clarifiers and bacteria supplements to help get the tanks water suitable for fish.

What products to use before you add the fish

It’s important that you use two types of products to get your tank cycling to enable your fish to enter healthy water.

  1. A good aquarium water conditioner which takes any chlorine and other chemicals out of the water that can hurt your fish. Most of these products also add a layer of protective slime onto your fish to help protect them. So always put this into the aquarium any time you add in new fish.
  2. Good bacteria, these are products that will give your tank a boost of biological bacteria that is designed to help breakdown the waste, leftover food and any other nasty’s in your tank. Click here for a list of the Bacteria supplements available.
    These need to be put into the tank before you add fish. It takes at least three - five days to get a tanks water settled. All of these products will help you settle the tank and have clear guides on the bottle to ensure that you use the correct amounts. You should also use them any time you add fish or do a water change to help give the tank a boost after it comes under a little more stress from either the new water or adding in extra fish.

How many fish should I have?

There are a few variables on how many fish you can have in a tank, one is the actual size of the fish when you get them and also the size of the fish when they are fully grown.

Here are some tips on stocking your tank:

Always err on the side of caution. You are much better to find that you don’t have enough fish as you can always add them, if you have too many fish you may find that some of your fish get sick or die due to having too much waste in your tank. This waste puts pressure on your aquarium filtration, which can cause your filters to overload and become unable to remove or breakdown the waste.
Always slowly build up your community of fish. It’s better to take your time to build up your community so that it doesn't put too much stress on your filtration. Even in a large tank start with just a few fish as this helps to start your biological filtration by feeding it some waste.
Here is a guide of how many fish you should have in your tank.

Fish compatibility

Not all fish are born equal so it’s important that you know what fish go with what. Some fish are passive and live well in a community, others are aggressive and generally only like to live with their own kind and sometimes own size of fish.

To help minimize any bullying in your tank we suggest that you have plenty of hiding places that your fish can hide or get away if they need to.

Observing your fish

The best way to really know what is happening in your aquarium is to observe your fish. Spend a few minutes getting used to the way they move in the tank, how they look, if there any fish that are bullying the other fish? This way if there are any changes to the way they interact or look you can seek some advice to ensure that everything is OK with your fish.

Aquatic food

Feeding your fish a variety of aquatic food will help to ensure they receive a nutritionally balanced diet. The research that goes into fish food is amazing, there are a lot of different types of fish it is important that your type of fish gets the food that is best suited to their needs.

What food to feed your fish

Where your fish lives in the tank is the first step in determining what food to feed your fish.

  • Top Dwellers - there are fish that live in the top of the water so need some food that sits on the top
  • Middle Dwellers - there are some fish that live in the middle of the tank these fish need something that sinks and floats slowly down to the base of the tank
  • Bottom Dwellers Fish Food - these fish generally live on the bottom of the tank
  • Algae Eaters - these fish need some greens in their diet

Types of aquatic food

Dry Fish Food

  • Fish Food Flakes - these are a dried flake that sits on the top of the water, once they have absorbed some of the water they start falling deeper into the tank so are great for most fish in your tank
  • Fish Food Pellets - these sink down so are good for fish that sit on the bottom of the tank or in the middle of the tank
  • Micro Fish Food Pallets - these are good for smaller fish that can’t get their mouths around a big pallet. As they are a pallet they will sink into the tank once they have taken on some water
  • Sinking Fish Food Pallets - perfect for the bottom dwelling fish, like catfish or loaches
  • Algae Fish Food Flakes - a good flake to add variety into your fish’s diet
  • Algae Fish Food Pallets - a good food for those algae eaters in your tank
  • Sinking fish food tablets - ideal for the bottom dwellers, like catfish or loaches

Gel Fish Food

Tetra has a gel fish food block that is packed full of nutrients and a great way to give your fish a variety of food. These are a great alternative to frozen food, and packed with more nutrients.

Going on holiday?

Fish are one of the easiest pets to care for while you are away. There are holiday fish feeders available for weekends or up to 10 days. Our advice is to try one before you go away and make sure that the fish like it and that everything is good. This way you can go away with confidence that your fish will be fine.

How much to feed your fish?

In the wild fish are opportunistic feeders, sometimes they have a access to a large amount of fish food so eat regularly, at other times fish food can be scarce so only eat when they can. Because of this fish will eat every time they get fed.

With this in mind over-feeding your fish is one of the greatest causes of high ammonia in your fish tank, so giving your fish the right amount of food is critical to ensuring that you don’t end up with leftover food in your tank affecting your water quality.

We recommend that all the food should be gone in 3-5 minutes to ensure that you are not over feeding. This takes a little bit of trial and error, but if you know the fish clean up all the food there is less chance of foods causing higher levels of Ammonia in your tank.

Testing your water

When thinking about water quality, it’s important to think about the fact that the very thing that your fish lives in is water, it is all around them, they ‘breathe’ it through their gills, so the quality of this water is critical to your fish’s wellbeing and ultimately survival.

You should test your aquarium frequently to keep an eye on any changes in the makeup of the water, and you should definitely check the water if your fish are looking sick or you have had a death in your tank.

What do I need to test for?

We recommend that you test your tank regularly and do a full test on the main four areas; nitrite, nitrate, ammonia and PH. When you first get a tank we recommend that you test the water once a week to get your head around what is happening with your water and how it changes. Is there anything you are doing that is causing these changes? Also if you have a high level in something what you do to bring these levels down.


When you are first starting up a tank the nitrite levels will most likely increase as the tank is establishing the biological filtration. High nitrite levels are a concern as high nitrite levels can stress or worse yet kill your fish.

If your nitrite increases in any way it is a concern that the biological filtration is not being as effective as you thought, so a water change is the best place to start to decrease the nitrites.


Although nitrates are not as toxic as ammonia or nitrites, they must be monitored to avoid stressing the fish. Nitrates can also be a source of algae problems.

If you have any level of nitrates we suggest a 20% water change, it is best to try and get on top of them as soon as you can.


Testing for ammonia is one of the most critical water tests. Ammonia is a build-up of waste, left over fish food & plant matter in the tank. If the biological filtration is not working well then there will be a rapid build-up of ammonia. We suggest you test for this weekly as you are unable to see ammonia build up. The only sign might be the fish gasping at the top of the water.

Once a tank matures ammonia can still build up if regular maintenance is not performed, with regular water changes, and filter cleaning, so regular maintenance helps to keep this down.

If you experience any ammonia in your tank, we suggest a 20% water change as soon as possible and retest the water within 24 hours, if you are still having trouble with ammonia then we recommend a further water change, make sure that your filter is cleaned out, and that you gravel syphon to remove as much matter as you can from the tank that may be causing the build-up.

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Written by The


Written by The Team

A team of specialists with backgrounds in animal nursing, animal care, and all things pet related.

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Tank Litres Goldfish to start with Goldfish approx 5-7cm Small Tropical Fish to start with approx 3-5cm Tropical Fish approx 5-7cm once fully stocked
20 2 2 to 3 2 to 3 4 to 6
40 2 4 to 6 4 to 6 10 to 12
60 3 6 to 8 6 14 to 16
80 3 8 to 10 6 18 to 20
100 4 10 to 12 8 22 to 24
120 4 12 to 14 8 26 to 28
140 5 14 to 16 10 30 to 32
160 5 16 to 18 10 34 to 36
180 6 18 to 20 12 38 to 40
200 6 20 to 22 12 42 to 44