Fishkeeping Guide

CHAPTERS

1. What to Consider Before Buying a Fish
2. Cycling a Fish Tank
3. Acclimatizing New Fish
4. How Many Fish Can I Keep in my Tank or Pond?
5. Calculating Pond and Aquarium Volume
6. How Often Should I Feed my Fish?

Find below a complete guide to the aquarium fishkeeping hobby, for beginners or experiended fishkeepers alike. To explore the fishkeeping hobby in depth, visit our blog pages via this link.

 

Chapter 1. WHAT TO CONSIDER BEFORE BUYING A FISH

As a responsible fish-keeper it is your duty to ensure you provide and maintain a suitable and healthy environment for your fish. Following these guidelines will help prepare you for the hobby.

1. Ensure you meet its welfare needs. Make sure you are prepared to accept the responsibility of caring for a fish properly and can provide the correct diet and habitat.

2. Ensure the fish is compatible with its new tankmates. Do your research online or contact us if unsure.

3. Ensure your aquarium fish tank or pondwater is dechlorinated. Click here for more information on removing chlorine from tap water.

4. Ensure your aquarium fish tank or pond is filtered and running before purchase. A fish tank should be fully cycled and running before adding fish.

5. Ensure your water parameters are right for your desired fish. Test kits are an essential item in your aquarium maintenance tool kit.
   

6. Do not buy fish as gifts or for third parties without consulting them. If you buy fish as a gift, ensure the recipient is aware and accepts the responsibility. Do not buy fish as a surprise gift.

 

 

Chapter 2. CYCLING AQUARIUM WATER

In simple terms, to cycle an aquarium means to establish a bacterial colony inside the filter to ensure that it is capable of breaking down harmful fish waste - ammonia.

A filtration system is a key component of life support in your fish tank or pond. You are relying on your filter to keep your water clean and fish healthy.

There are two ways to effectively cycle a fish tank - by using a small colony of fish, or the fishless cycle.

 

Cycling a Tank with Fish

A good way to understand how filter bacteria establishes, is to imagine what would happen to your bathroom toilet if you left it uncleaned for a few weeks. Think of the number of bacteria that would build-up on the pan!

Cycling a fish tank is practically the same process, because you are relying on the fish’s toilet habits to encourage bacteria to grow in your filter. When fish go to the toilet, they produce ammonia. The bacteria that develop on your filter will feed on ammonia to survive, reducing the levels present in your water.

If using this method, it is important to use only a small colony of hardy fish, like guppies, that will not turn belly-up when exposed to moderate ammonia. It is important not to add too many fish, as this may cause harmful levels of ammonia to form, or "spike", which could be fatal to your fish.

 

The Fishless Cycle

The most common method used when establishing a new tank, particularly by beginners and those new to the hobby, is the fishless cycle.

This is where you manually add ammonia and/or filtration bacteria, to help "start" your aquarium filter. It does not require the use of live fish.

To perform a fishless cycle, fill your aquarium with water, power-up the filter and add filter starting bacteria. You can find examples of filter-starting bacteria via this link.

There are many "quick-start" treatments out there that will speed-up the cycling of a new tank, which is handy if you need to setup an aquarium in a hurry or emergency, but it is recommended that you allow as much time as possible to create a suitable habitat for you fish.

 

Timescale

Patience is key to the effective cycling of a fish tank. Cycling a cold-water or tropical aquarium usually takes around 5-7 days. Marine aquariums can take quite a bit longer!

It is very wise to test the level of ammonia present in your tank before adding fish, even if you have completed a period of cycling. You can browse our test kits via this link.

 

Recommendations

Remember that Ammonia and Nitrite can be lethal to livestock. Ammonia can also be produced by rotting plant matter, dead livestock, and uneaten food. Take care to manage these aspects responsibly. Follow these golden rules to keep aquarium water cycling:

 

1. Always allow as much time as possible to cycle your aquarium - ideally 5-7 days or longer.

2. Do not be in a hurry to add too many fish at once - you do not want to overload the filter with ammonia.

3. Buy a test kit to monitor ammonia levels. Test kits are available via this link.

4. If your ammonia levels are high, it may suggest that you have too many fish or an ineffective filter.

5. Use a regular supplement of filter bacteria to cultivate your filter colony. Good bacteria are available via this link.

6. A 10-20% water change is recommended each week to help reduce nitrate. Clean your filter sponges when water flow reduces, and use only aquarium water to rinse filter sponges, to avoid loss of beneficial bacteria.
   

 

The Nitrogen Cycle

This helpful diagram will show you how ammonia is processed through your filter:

Harmful ammonia is first broken down into nitrite, and further processed into nitrate. A good test kit will read the levels of ammonia, nitrite, and nitrate in your aquarium water.

 

Ammonia and nitrite can be potentially lethal to your fish. You will want to keep these levels low. Nitrate is less harmful to your fish and can be absorbed by live plants as an effective fertiliser. Nitrate is diluted and reduced by performing regular water changes.

 

It is good for all responsible fish keepers to know about the nitrogen cycle as it can give you a better understanding of what is going on inside the fish tank, and how to potentially resolve any problems that arise.

Keeping your aquarium well oxygenated will also help the breakdown of ammonia. You can find air pump kits via this link.

 

 

 

 

Chapter 3. ACCLIMATIZING NEW FISH

All fish are sold on the provision that they will be acclimatized, responsibly cared for in good quality water, and kept only with compatible tank mates. Always ensure you have used a suitable dechlorinating tap safe product in your aquarium water.

Follow these steps to safely introduce your new fish:

1. Turn your aquarium lights off. Bright lights can stress-out your new fish, especially after a long journey in a dark box.
   
   
2. Feed any other fish in your tank to minimise their interest in the new fish.
   
   
3. Float the closed bag in the water, allowing the water temperature in the bag to synchronise with the water temperature in the tank.
   
   
4. After 10 minutes, open the bag and fold down the sides so that it remains afloat at the surface.
   
   
5. Introduce a small amount of current aquarium water into the bag, so that it mixes together. This will give the fish a taste of their new conditions. Repeat every five minutes, until the bag has floated for at least fifteen minutes.
   
   
6. If you do not want to mix the bag water into your aquarium, use a small net to catch and transfer your fish into their new home.
   
   
7. If you are happy to mix the bag water into your aquarium, discard three quarters of the water in the bag. And slowly tip the bag upside down to release the fish into the tank.
   
   
8. Leave the lights off for at least 2 hours, or until the following day if you can.
   
   
9. Feed your new fish a small amount once settled, and then continue your normal feeding routine ongoing. We feed our fish once a day, in the evening, a mixture of flake and granules.

 

Stress

If your fish show signs of distress (e.g., paleness, lethargy) due to acclimatizing, please monitor them closely for 24 hours after step 9.

 

Quarantine

Though not essential, it is good practice to quarantine all new fish before introducing to your tank.

Placing your new fish into a segregated habitat or quarantine tank that mimics the conditions in your main tank for a period of 48 hours or more will help the fish adapt to the new water chemistry and prevent the increased potential for common diseases due to acclimatising stress around your current livestock. We know that this is not always possible, so we offer the following assurances.

 

 

 

Chapter 4. HOW MANY FISH CAN I KEEP IN MY TANK OR POND?

Here we explore the questions frequently asked about fish stocking densities.

 

What does Stocking Density mean?

Stocking density refers to the ideal number of fish that a pond or aquarium can hold to ensure optimum welfare and minimal stress. Getting the livestock density correct will help you to manage the ammonia and nitrate levels effectively and ensure good water quality.

 

Why are Stock Density Levels Important?

The most important factor when calculating livestock density levels is to consider the amount of waste the fish will produce and ensuring that your filter is adequate enough to handle the water pollution. Calculating fish stock density ensures that you do not encounter losses due to poor water quality.

 

Stocking Density Guidelines

The generally accepted rule in most local tropical fish stores, is one “thumb-sized” fish per 10 litres water. Although this can slightly differ per species and water type.

Stocking Density can be broken down into the following formulas:

 

Coldwater Fish: 1x one Inch (2.5cm) fish per 5 litres

Tropical Fish: 1x one Inch (2.5cm) fish per 5 litres

Marines: 1x one Inch (2.5cm) fish per 20 litres

Pond Fish: 1x ten Inch (25cm) fish per 500 litres

 

For example, to calculate how many 1” inch tropical fish can fit into a 100L aquarium, use the following calculation: 100L divided by 5 = 20 fish.

To calculate how many 1” inch marine fish/inverts can fit in a 100L aquarium, use the following calculation: 100L divided by 20 = 5 fish.

 

Quick Reference for Popular Aquarium Volumes

Tropical and Coldwater (1” fish)

25L = 5 x 1” fishes

50L = 10 x 1” fishes

100L = 20 x 1” fishes

200L = 40 x 1” fishes

250L = 50 x 1” fishes

300L = 60 x 1” fishes

350L = 70 x 1” fishes

500L = 100 x 1” fishes

If your chosen fish is larger than one inch, divide the answer above by its total length. For example, if the fish is 2” in size, a 100L aquarium will hold 10, rather than 20 (Twenty divided by 2)

 

What to Consider when Creating an Aquatic Habitat

There are a few things to consider when stocking your habitat. Fish need to have room to swim and must be able to co-exist with the other inhabitants. Some fish are territorial, and in order to ensure they can coexist peacefully, considerations must be made towards providing adequate territory and avoiding the potential for conflict to take place.

Some species, like Oscars and many fancy goldfish, will grow significantly and require extra space when they reach full size. Always check the maximum size when planning for habitation long-term. With large-growing species, purchasing a habitat to house their fully-grown size is wise.

Small (1-2”) fancy goldfish, for example, are recommended to be held in starting habitats no smaller than 35L to allow for extra growth. A responsible fish keeper will upgrade their habitats over time if the fish are outgrowing the space.

 

Avoiding Territorial Conflict

It is important to ensure you have enough floorspace, or surface area, to provide suitable habitat for your fish. For species that are territorial, not having enough territory can lead to conflict and even fish death due to fighting or stress.

For example, if you are keeping plecos, you must ensure there is room for driftwood, or caves. If you are keeping certain cichlids, you must ensure adequate territorial space to limit the aggression. Housing too many territorial species in a small space will lead to conflict.

Mixing up territorial needs can be tricky, but you must ensure each territorial fish has enough space to establish their territory, and not be in conflict with or overlapping the territory of its neighbours. You may need to lower the stocking density as a result.

 

Exceeding Recommended Stocking Densities

Stocking densities are set as guidelines for the fish keeping hobbyist, to enable long-term healthy aquariums. There are many cases where densities will far exceed recommendations, such as fish farms or your local fish store – but these places will often be moving fish on swiftly and in large quantities, in heavily filtered tanks, long before any water quality issues will occur.

Overstocking outside of the expertise of agricultural practice should generally be avoided, or you will likely experience water quality problems.

 

Other Things to Consider

1. When heavily stocking tanks, a well-circulating and oxygenated aquarium is recommended.

2. If you are stocking a cylinder or column-shaped tank, these will often have a lower surface area, or floor space. You will need to take this into consideration when considering the territorial needs of your fish.

3. Using extra filtration or over-filtering may not necessarily allow you to stock a higher density of fish. The more fish you keep, the more nitrate they will produce. Nitrate can be tackled and diluted through frequent water changes, and not necessarily via extra filtration.

4. Remember that fish will grow – always check the maximum size they can grow to and house them based on long-term calculations.

5. Pond water levels will decrease significantly in hot weather and increase during heavy rainfall. You may lose water volume due to evaporation, so top-up during the hotter months.

6. Consider that many live-bearing fish such as guppies, mollies, and platys, will produce fry. Allow extra space for potential new arrivals!

 

 

 

 

Chapter 5. CALCULATING POND AND AQUARIUM VOLUME

In simple terms, “volume” means how much water in litres your aquarium or pond will hold.

 

What to Consider when Calculating Volume

It is always wise to consider what may be displacing the water in your aquarium or pond. For example, if you have gravel, plants, or many rocks or ornaments, each of these will be taking up space, and displacing water.

So, a 200L aquarium may only be holding 180 litres of water, because the plants, rocks, gravel, or ornaments are taking up volumetric space. Always consider what may be taking up tank space when calculating volume.

For example, a 100 Litre tank with 5kg gravel inside will only hold 95 litres of water, because the gravel is displacing 5 litres (5kg is equivalent to 5 litres)

A general rule to follow for common aquariums is to knock 10% off your volume calculation if you have gravel or décor in your tank. So, a 100L aquarium less 10% water displacement is 90 litres.

 

The formula for calculating aquarium volume is as follows:

Length x Width x Height (cm) divided by 1000.

So, an aquarium measuring 50cm (L) x 30cm (W) x 25cm (H) holds 37.5 litres.

Calculation: 30 x 50 x 25 = 37500; divided by 1000 = 37.5

To allow for 10% displacement as described above, use the following formulas:

37.5 divided by 100; multiplied by 10 = 3.75
37.5 minus 3.75 = 33.75 litres (volume less displacement)

You can substitute the value 10 for whatever percentage you determine is displaced. If it is 20%, change the value 10 to 20.

 

Calculating the Volume of a Pond

Calculating volume is also vital for determining the correct amount of chemical treatment additive to add for disease or water conditioning in your pond or aquarium. Over or underdosing can be detrimental to fish health. It is also vital information to have before the addition of salt to pond water.

 

The formula for calculating pond volume is as follows:

Length x Width x Depth (Metres) x 1000 = Volume in litres.

So, a pond measuring 2.5m length x 1.2m width x 0.4m (40cm) depth holds 1200 litres.

Calculation: 2.5 x 1.2 x 0.4 x1000 = 1200 litres.

 

To allow for varied shapes of ponds:

If your pond is an uneven shape with differing depths or width, calculate the average measurement.

For example, if the pond is kidney shaped, take various depth and width measurements at different points.

If it is 2m deep at one point, and 2.5m and 3m deep in other sections, calculate the average by adding the measurements together and dividing by the total number of measurements taken. You can also do this with width, by taking width measurements at various points where width changes.

 

The formula for calculating average width or depth:

The So, in the example above the average width is 2.5m.

Calculation: 2 + 2.5 + 3 = 7.5; divided by 3 = 2.5

Use this average figure in your volume calculation for width (2.5m)

 

 

 

 

Chapter 6. HOW OFTEN SHOULD I FEED MY FISH?

Fish-keepers regularly have their own routines for feeding, often built-up after many years of experience. Many will feed as part of a daily routine, or to suit growth patterns, or breeding. Ultimately, when you get to know your fish, you will develop an instinct for their frequency of feeding.

The most common routine for common tropical or cold-water fish, is to feed once a day, as much food as they will consume in one minute. This will ensure basic survival.

To achieve growth, feed a high-protein food source twice a day, following the same principle of feeding as much as they will consume in one minute. Be aware that this method will produce more waste, so you will need a filter that can handle the strain, and regularly perform water changes.

Cold-water fish, like goldfish, often have the potential to grow very large. So as long as your habitat size allows for extra growth, it is recommended that you feed them twice a day.

Pond fish will again follow the same principle. Many keepers of ornamental Koi will feed them high-quality food, often twice or more per day, to achieve maximum growth and colourful vitality. Be aware that pond fish will stop feeding over the colder winter months, so bolstering them with a dense feed, such as wheatgerm, in the build-up to winter will help them get through until spring.

Always ensure that any uneaten food is removed from the aquarium or pond after a few minutes. Uneaten food will decompose and potentially clog filtration, adding unwanted ammonia to your aquarium, and can attract pests or rodents to your garden pond.

 

Flake Food

Dried flake is the most common and complete food for aquarium fish, anywhere in the world. It is often a composite of high-protein food, with added vitamins and minerals.

Flake can be sprinkled onto the surface, or to avoid issues such as swim-bladder in larger species, you can hold a pinch under the surface, so it saturates and sinks.

Flake will often produce low waste, breaking down quicker than alternatives.

 

Granules

Granular food is very similar in composition to flake food, being made up of high protein and vitamin rich feed, often derived from insects.

Granules are designed to be eaten by smaller fish, like neon tetra, being easier to swallow and requiring less digestive effort to process. Many granules are specifically designed for species such as Betta fish, or shrimp.

Granules will often produce low to moderate waste, breaking down slowly on the aquarium floor.

 

Algae Wafers

Algae wafers are derived from natural algae and meat-free additives. Primarily designed as a complete feed for Herbivores, such as plecos and snails, they will also be grazed upon by omnivores, and can be broken-up and fed to species such as cichlids and rams.

Plecos, snails, and shrimp will thrive on algae wafers which can be given as a complete feed for such species. Algae wafers will produce a fair amount of waste if uneaten, but will often take a lot longer to decompose, so can be left in the aquarium for a longer period of time.

 

Pellet Food

Pellets are often designed for larger species, such as cichlids or outdoor pond fish. Take care to determine whether floating or sinking pellets are more suitable for the species you keep. Outdoor pond fish will often have a different pellet feed depending on the time of year, with goldfish requiring floating pellet, and other species like Sturgeon or Tench benefitting from sinking pellet.

Because pellet feed is so dense, and packed with protein and additives, you often only need to feed a small amount to give your fish what they need. Offer your pellet-fed fish a bit of variety, there are many different types of pellet which should stop them getting bored of repetitive food.

Take care to choose the right pellet feed, and monitor wastage. Many pellet foods will produce a lot of waste or leave an oily residue on the water surface, so good filtration is recommended.

 

Live Food

Live food is about as close as you can get to replicating a natural diet in the wild. Mosquito larvae, bloodworm and shrimp provide a challenge to your fish to catch and forage for while wriggling around in your aquarium.

Live food must be brought as fresh as possible, you do not want to be adding decomposing food to your aquarium. Always ensure you buy them as fresh as possible, from a refrigerator. Enquire as to when your local supplier receives their delivery and get in quickly. If their stock arrives on a Tuesday, you do not want to be buying what is left on Friday.

 

Frozen Food

Frozen food also replicates a more natural diet, with fresh ingredients such as bloodworm and shrimp providing a premium alternative to dried feed, storing longer than live food.

You do not necessarily need to thaw vegetable, worm or shrimp-based frozen food before adding it to your aquarium, especially blocks intended for smaller fish. Frozen food blocks will start to melt as soon as they hit the water, as aquarium water is often warm, or at least warmer than a frozen block. If you keep sensitive species, such as gourami, or cold-water species, like goldfish, allowing frozen food to thaw at room temperature for at least ten minutes will prevent any ice-related mouth injury.

Larger blocks, often intended for predatory fish, such as beef-heart of whole mussels, will need to be thawed thoroughly. Predatory or larger fish will often swallow frozen blocks whole, which is not recommended. Leaving them to thaw for a couple of hours in a sealed box at room temperature is fine – make sure it is in a sealed container, because frozen fish food can be really smelly!

You can use a worm-feeder, or float a funnel on the aquarium surface, to gradually thaw and introduce frozen food into your aquarium. Adding frozen blocks into floating funnels will gradually melt blocks into your aquarium – but do be aware that medium to large fish will potentially attack and knock the funnel or feeder in a hungry frenzy, which can be damaging to both.

If you are purchasing frozen food online, they will often be delivered in thermal poly-boxes which are in transit for a couple of days, so some thawing will occur. You must ensure that the food is put straight into the freezer to fully re-freeze, it is not recommended for use straight away.

Frozen food is provided in sterile packaging, so you can refreeze it as long as the packaging is not open or breached. Once opened, do not refreeze.

 

Additional Food

If you do a little research, you will often find that you can supplement the diet of the species you keep with food commonly found around the household.

Many omnivore and herbivores will happily dine on vegetables. Iron-rich broccoli, spinach, peas, and cucumbers are often added by experienced fish-keepers. Species such as Plecostomus and snails will thrive on fresh or even slightly turned vegetables. Carnivores and predatory species may also be partial to raw meat.

You must be careful not to use anything that may have been exposed to pesticide. For this reason, using organic vegetables is highly recommended. If you grow your own vegetables, and do not use pesticides or fertilisers, you can use your offcuts such as broccoli stems, pea shells or courgette leaves.

Many invertebrate species, such as snails or shrimp, will thrive on sources of calcium, like cuttlebone or vacation blocks. You can even use powdered calcium, though research is required to not disturb aquarium PH. Calcium will ensure healthy shell and carapace growth, and you will notice that many shrimps and crabs will shed their shells and feed from the remains – this is a good source of calcium and minerals so can be happily left inside the aquarium

Be aware that much of the food mentioned above will float, so you may need to weigh-down any vegetables that you add. If it looks like your fish are not eating the food, remove it after a few hours. Do not leave any raw meat to decompose, or you may end up with unwanted worms or parasites. Take care not to add any food with a strong odour, like leek, or your room will end up smelling very oniony!

 

Compiled and written by: M. Chinnery / C. Carter, last updated September 2024.

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