FAQs Tropical Fish

FAQs Tropical Fish

Tropical Tank FAQ's

What's the best size of aquarium for a community set-up?

If you choose your fish carefully, it is possible to set up a small-fish community in aquaria of 45 x 25 x 25cm/18" x 10" x 10" or less. But we would advise you to get the biggest tank you can afford and accommodate.

The larger the body of water, the easier it is to keep the water conditions stable and prevent ammonia and nitrite spikes. It will need a stand or support that can take the weight (water is extremely heavy) and it's best to position it away from draughts, heaters, loud noise and direct sunlight. Locate it close to power points to prevent problems with trailing wires, etc.

How many fish can I keep?

This all depends on the volume of water in your tank. Knowing the volume is also very important when it comes to adding medications to your aquarium.

To calculate the volume, multiply the length of the tank in feet by the depth and then multiply this result by the width. Multiply this by 6.25 and then take off 10% for water displacement by substrate, rocks and other decor. This may sound a bit complicated, but it's actually quite easy to do.

Example:In a 36" x 15" x 15" aquarium you would multiply 3 x 1.25 x 1.25 = 4.68. 4.68 x 6.25 = 29.25 gal. - 10% = 26 gal.

If you wish to convert this figure to litres, just multiply it by 4.55.

In a tropical community aquarium you can have 1" of fish per gal. (2.5cm per 4.55 l.) initially; rising to 2" per gal. (5cm per 4.55 l.) after six months as a suggested maximum.

So in our 36" x 15" x 15" aquarium we could keep 26"/65cm of fish, rising to 52"/135cm after six months, as a sensible maximum.

Please could you recommend some beginner's plants for the community tank?

Try Hygrophila corymbosa, H. stricta or H. polysperma, Wisteria and Ludwigia (especially repens and the green variety). Heteranthera zosterifolia is also good for new set-ups as it is inexpensive and fast growing.

Others to consider are most of the Cryptocoryne species, such as wendtii and becketii along with some of the hardy bulbs like Aponogeton crispus and Nymphaea stellata, and any of the Crinum spp. You can also grow floating plants like Riccia and Amazon Frogbit.

Many retailers also sell terrestrial plants for aquariums - although these will look nice for a while, they will soon begin to fall apart and die, as they are not really suitable for life underwater. These include Spathiphyllum sp. (Peace lily) and Dracaena sp., both of which are actually houseplants! Avoid them.

Rather than using just gravel as a substrate try a 50:50 mix of fine silver quartz gravel or silver sand and a nutrient-rich substrate like Seachem's Fluorite or Onyx. This will be more expensive, but will give you better results.

Why do I need to do water changes and how often should I do them?

Even in a well-filtered tank, the water gradually gets more and more polluted - nitrate and phosphate levels rise, and the pH level can drop. Remember that your fish are swimming in their own toilet!

Partial water changes help to remove wastes, diluting dissolved pollutants and restoring minerals.

We recommend you change 25% of the water every week or two to keep it in the best condition, but more may be required for your tank.

One way to find out whether your current maintenance regime is effective is to test the nitrate level in the tank and compare it to the nitrate level of your tapwater. If you are changing enough water, the nitrate level in your aquarium should be only slightly higher than that of your tapwater.

If it's considerably higher, increase the amount of water you change each time, or do more frequent water changes. Increased phosphate, or a reduced pH in the tank, may also be a sign maintenance needs improving.

Partial water changes can be combined with gravel syphoning to remove any solid matter that can accumulate in it.

Why do I need to treat my tapwater with a conditioner?

Tapwater contains added chlorine and sometimes chloramine, which kill bacteria and other organisms making it safe for us to drink.

But while they are fine for humans, both chlorine and especially chloramine are dangerous to fish and the essential bacteria that break down the fishes' wastes. Adding untreated tapwater can stress or even kill fish, and quickly wipes out filter bacteria which can result in pollution problems for several weeks.

Any tapwater added to your tank needs to be treated with a dechlorinator (water conditioner) to remove chlorine and always wash filter media in a bucket of old tank water, never under the tap!

Well over 10% of the UK's tapwater contains chloramine. This is a compound of chlorine and ammonia, and when it's neutralised by a standard dechlorinator it leaves the ammonia behind.

How do I know which fish are best for my water conditions?

Pay a visit to your nearest aquarium shop which will most likely have the same water supply as yourself, and will therefore know which species fare best in the local tapwater. Many of the popular community fish will live quite happily in most types of UK tapwater.

Some more specialist fish like Discus prefer soft, acid conditions, whereas Rift Lake cichlids like hard, alkaline conditions. Always read up on any fish before you buy it to ensure that its requirements regarding water chemistry are compatible with the rest of your stock, that its temperament and potential size won't cause problems in the community tank, and that it doesn't have a specialised diet that might be difficult for you to provide in a community tank situation.

What fish can I add to control an outbreak of snails?

The Candy stripe loach, Botia striata, and the Pygmy chain loach, Yasuhikotakia (Botia) sidthimunki, are often recommended and for tanks of around 120cm/48", the Clown loach, Chromobotia (Botia) macaracantha, is a good choice.

All are happier in groups of four or more. The Striped talking catfish, Platydoras costatus, eats snails but can get quite big and may eat small fish, so is best avoided in the community. Puffers are good snail eaters, but can be aggressive and often nip fins.

I have recently set up a new community tank, but I keep losing fish. What's going wrong?

It could be that you've stocked too many fish too soon, leading to a problem called New Tank Syndrome.

To work effectively, a filter needs to have a large population of friendly bacteria present. These bacteria consume toxins in the water, such as ammonia, that arise from the waste produced by the fish, uneaten food etc. and turn them into less harmful nitrite and finally nitrate.

It takes at least a month for these bacteria to multiply to a level where they can consume all the wastes in the water. This is often called 'the maturation period' and it's vital that you don't add too many fish at this stage, or overfeed, for if the pollution levels get too high, your fish may become sick, or even die.

Test your tank water for the presence of ammonia and nitrite (or take a sample to your shop for them to test for you). Both levels should be zero - if not then you need to carry out a water change and monitor the conditions closely, carrying out a water change if the levels begin to rise.

Don't add any fish while ammonia or nitrite is present in the water and keep feeding to a minimum. Stock slowly. Start with two or three hardy fish and build up with monthly additions of three or four.

My tetras and barbs seem fine, but my Corydoras have lost their barbels. What could be wrong?

It's important when keeping fish like Corydoras and other catfish that live and feed off the tank floor, that your substrate is clean. Otherwise they can be at risk of bacterial infection. This may erode the barbels and result in the death of the fish.

Each time you do a water change, use a gravel cleaning syphon (available from your retailer) to suck the dirt out of the substrate, rather than just removing the water from above it.

Gravel cleaning is particularly important if the tank is fitted with an undergravel filter, since the filter bed will block unless the dirt which collects there is removed.

Sharp gravel may also wear away the barbels as the Corydoras nose around in it for food - although many fishkeepers successfully keep them in tanks with gravel substrates, most experts agree that aquarium sand is better for keeping Corydoras.

I'd like to keep gouramis in my community tank. Which are best?

One of the most commonly sold gouramis is the Dwarf gourami, Colisa lalia, but those sold today are often not as hardy as those available a decade or so ago. In addition, the males tend towards one of two extremes - they either hide constantly or are aggressive. They can also be pretty hard on the females which can end up leading a miserable life.

The Honey gourami, Colisa chuna, (5cm/2") is a much better bet. They might not look so colourful in the retailer's tank, but they soon colour up once they're settled in. They can also be kept in groups. Croaking gouramis like Trichopsis vittatus (7.5cm/3") and the smaller T. pumilis are also good choices.

If you have an aquarium of 90cm/36" or more, the Thick-lipped gourami, Colisa labiosa, Moonlight, Trichogaster microlepis, and Pearl gourami, T. leeri, are good choices.

Kissing gouramis, Helostoma temminckii, are really only suitable for larger community tanks. They can reach 15cm/6" or more.

The Three spot gourami, Trichogaster trichopterus, is available in a number of colour forms, but it can be spiteful in the community. Avoid also Chocolate mis, which are difficult to keep, and the Giant goramy, Osphronemus goramy, which gets huge...

Can I keep a Siamese fighter in my community tank?

This is a difficult one. Some fishkeepers do successfully keep them in community set-ups, but in many cases their long, flowing fins are a magnet for any fish that's likely to nip and they end up looking rather tatty and miserable.

If your water quality is slightly below par, this damage can lead to infection.

My female Guppies are regularly pregnant, but I never see any babies. What's wrong?

This a common problem with livebearers in the community tank as the newborn fry are often eaten (the parents will also eat their own fry). Lots of fine-leaved plants provide hiding places for the babies.

Alternatively, watch out for the female getting plump in the belly region, then transfer her to a tank with plenty of real or artificial plant cover, where she can give birth. Remove the female afterwards. Breeding traps can be too confining for the female, causing her to panic and miscarry.

Feed the fry on freshly hatched brineshrimp or one of the special foods for baby fish. Once the babies are around two weeks old, you can crush normal staple flake food and feed that instead.

How often should I change my bulbs?

If you're growing plants or corals, you'll need to change the bulbs each year. Although they will still give off light, the light produced isn't of the same quality or spectrum as it was when the bulbs were new.

Replacing the bulbs will bring the light levels back up and allow the plants to grow properly. If you don't grow plants, there's no need to replace the bulbs until they get dimmer, flicker or fail completely.

How long should I leave the lights on for?

Leaving the lights on for too long can encourage algae to grow. If you're growing plants or corals, you ought to leave the lights on for around 12 hours each day as this is the typical amount of sunlight they'll be used to in nature.

You can get a cheap timer to plug your fluorescent lights into for about a fiver from IKEA. If you don't grow plants or corals, just switch on your lights in the evening. The daylight from your window is adequate, you'll minimise the amount of algae you get, and save a few pounds on electricity.

Do I need a reflector?

It's advisable to add a reflector to your bulbs, otherwise much of the light emitted is absorbed by the hood. Adding a reflector could increase light levels by up to 80%.

How does a heater work?

Virtually all aquarium heaters use a bi-metallic strip thermostat to control the flow of electricity to a simple heating coil.

The strip, as the name suggests, is made from two different metals that expand and contract at different rates when the temperature changes, which causes the strip to bend away from an electrical switch inside. When the water gets warm, the strip bends outwards and cuts off the supply of electricity, preventing the tank from getting too hot.

When the water cools, the strip contracts and closes the circuit, switching the coil on and heating the water again. Bi-metallic strips can be capable of detecting temperature changes of about +/- 0.25?C, but unfortunately, they tend to go wrong sooner or later. And when they do go wrong, they may overheat the tank and can kill fish if you don't spot the problem quick enough.

How can I stop my fish damaging themselves on my heater?

Get a heater guard. Most manufacturers make one designed to fit their heaters, but you can also get generic ones that fit most brands. This protects the heater from knocks and stops the fish leaning against it and burning their skin.

What are the benefits of an external filter?

Besides the obvious bonus of not being visible inside the tank, externals usually have much more space inside for filter media than internals do, and you can usually fill them with the media of your choice.

The extra media volume means that there's more space available for bacterial colonisation, so the filter is capable of supporting more fish (or rather more pollution) than a smaller filter, like an internal. Externals arguably need less maintenance, too.

What are self-priming externals, and why might I want one?

Externals work by drawing in water via a syphon. As such the inlet hose and canister need to be filled - and the hose must be syphoning - when you try to start up the filter or it will try to empty itself and run dry.

Self-priming externals have gadgets, like plungers and refill-inlets, to allow you to fill the body up and start the filter. Without this, you'd need to suck on the inlet or the outlet to get the filter going.

Filters without this feature are now considered a little old-fashioned.

How do I clean my external?

Switch off the mains, shut off the taps attached to the hoses and place the filter in a cat-litter tray (a clean one would be good) or an old washing-up bowl to catch spills.

Remove the sponges, or other mechanical media, and wash them in a bucket of water from the tank. If the biological media is dirty, it's worth giving this a gentle rinse, but it can usually be left untouched.

Chemical media can need monthly replacement, depending on the manufacturer's recommendations.

Never use tapwater to clean filter media - the chlorine and chloramines present will destroy the filter bacteria.

Once you've cleaned the filter, reinstall the media, connect the motor housing, turn on the taps, prime the filter and power it up.

Externals don't always start the first time, so you might need to re-prime the filter by filling it and the inlet pipe with water to get it going again.