Aquarium Fish: How To Stock Your Tank

Aquarium fish: How to stock your tank

It’s all very well to hear people talking about the beauties of an aquarium, how to maintain adequate pH, keeping nitrate and phosphate levels adequately balanced, and so on … there seems to be plenty of technical detail available!

But what about the actual fish? How do you choose which ones you want? How do you know whether they’ll be too big for the tank when they grow up, or whether they’ll be compatible with your other fish? How do you find out how to stock your tank?

Here is a quick rundown of the things you’ll need to bear in mind when choosing fish for your tank, as well as a brief look at a couple of the more common types of tropical fish. Hopefully it’ll give you a good idea of where to get started!

Freshwater vs. Saltwater

Obviously, the water type is different, but what does that actually mean in terms of the kind of aquarium you’ll end up with?

Specifically, freshwater tanks are generally recommended for beginner aquarists – especially if children are going to be involved in looking after the fish.

This is because freshwater fish are much easier to look after, and are generally more resilient to less-than-perfect water quality and fluctuations in temperature (and, really, all the sorts of mistakes that beginners are prone to make!). In general, freshwater tanks are both cheaper and easier to maintain than saltwater ones.
Saltwater aquariums often have more colorful fish, but maintaining the chemistry of a saltwater tank is a pretty finicky business, and is best undertaken by someone well-versed in the lore of fish-keeping.

What to think about when choosing your fish

Unfortunately, choosing fish for an aquarium isn’t as simple as you might think. You can’t just go into a pet store and select arbitrary numbers of the fish that you find the most appealing – you need to invest some forethought into your tank to ensure that your fish lead happy, healthy lives.

Some things to think about:

• Fish size. When you buy fish, they’re usually babies. Some will stay about the same size, but other will grow much, much larger – so you’ll need to bear the size of your tank in mind! As a standard rule of thumb, always buy for the adult size. If there’s no guide on the tank or if you’re unsure, ask the assistant. This is really important, because fish are sensitive little creatures: if they’re subjected to overcrowding (which happens when fish are too large for their surrounds), they can get so stressed out that they die. Really.

• Recommended diet. Not all fish dine equally – some fish eat live food, some eat frozen food, some eat flakes, and some will eat anything (but don’t rely on that last one when it’s tank-stocking time!) Because different fish eat different things, unless you’re prepared to invest time each day in measuring out the accurate quantities of various fish foods, it’s best to get fish that eat the same thing. It’ll make it easier and less expensive for you to take care of your new pets (and will ensure that the kids can participate, too, if they want to get involved).

• Compatibility. Contrary to popular belief, fish do actually have personalities – and some of them can get pretty aggressive. Many tropical fish have well-deserved reputations as bullies: they can nip the fins of other, more peace-loving fish, they can ‘barge’ smaller fish, and they can get into fights (which are frequently pretty vicious). To eliminate the likelihood of your fish getting into scraps, you should aim to buy fish that have mutually compatible personalities – which means, no territorial fighting fish in with a school of peace-loving roamers!

• Water temperature. Just because the dozen or so species of fish in that wall of tanks in the pet store are all labeled ‘tropical fish’, doesn’t mean that they’re all tropical fish from the same region. Different fish thrive in different temperatures – and because you can only have one temperature at a time in your tank, it’s best if you choose fish that are comfortable in the same temperature range.

• Life expectancy. Some fish live for upwards of ten years – which is a pretty serious time commitment! If you’re a free spirit who likes to roam about (and, let’s face it, tropical fish tanks don’t normally go down so well when you’re trying to thumb a ride), consider how long you’re likely to want to keep this fish tank for, and shop accordingly.

So what types of fish can I buy then?

Shopping for tropical fish is fun! As long as you’ve got your tank dimensions figured out and know basically how much money you want to spend (and have perhaps printed out the above list, to take with you to the store), grab your wallet and head to the pet shop/fish breeder. One of the best parts about keeping a tropical tank is that the beauty of the fish doesn’t depend on the size of your checking account!

Some common breeds that you’ll likely encounter:

• Clown Loach. Clown loaches are colorful, lively, and humorous fish with plenty of quirky personality traits (like lying on their side when resting, and making loud clicking noises when they eat!) Clown loaches do best in schools, so if you like them, get at least three or four. These fish grow between 6 and 12 inches – they’re pretty sizeable! – and prefer to eat meaty food.

• Congo Tetra. These peaceful fish are popular choices for beginners, as they’re very brightly colored and like to flash around the tank in divertingly attractive schools (again, you’ll need to get more than a few of these to keep them happy). These are a medium-sized fish, generally growing to around 5 inches in length, and require a minimum of 30 gallons of water for adequate swimming space. Tetras love clean water, and lots of live plants to dart around and hide behind, but aside from this they’re pretty easy-care.

• Elephant Nose. These are really amazing fish to look at – they have a long, protuberant ‘trunk’ for a nose (hence the name) which they use to hunt small live food - although they will also eat frozen and flaked food too, if it’s all that’s available. They grow to be about 8 inches long and need a sandy, gravelly bottom on the tank. These are fairly territorial fish, but will do fine as long as the tank isn’t overcrowded.

• Tiger Barb. These fish derive their names from the characteristic black barring (‘tiger stripes’) on their flanks. They’re very striking fish, but they can be quite aggressive toward other species (they’re known as fin nippers). Aggression is minimized by keeping them in schools, where they’ll be distracted from the other fish in the tank by working out the necessary hierarchy among themselves – it can be pretty diverting to watch! Tiger Barbs grow to about 3 inches and need plenty of space for schooling. They’re omnivores, so they eat all types of food: the one feeding rule is to do it regularly, to avoid aggression!

Further Reading

For more information on the technicalities of keeping a tropical fish tank, check out Katy’s Tropical Fish – A Complete Guide. As the title promises, it’s a complete compendium for the responsible fish-keeper of any experience level, and is packed from start to finish with valuable gems of relevant, detailed, and easy-read information.

Tropical Fish: White Spot

Tropical Fish: White Spot

White spot is arguably the most common disease that tropical fish are subject to, and is believed to be responsible for causing more fatalities than any other disease. Most – if not all – aquarists will encounter white spot (also known as Ich) at least once or twice during the course of their career/hobby.

What is it?

White spot is a single-celled, ciliate protozoan. In regular English, this means it’s a single celled parasite organism, which propels itself through the water through use of cilia, or filament-like hairs. Mature adult cells are 0.5 – 1.0 mm in size, and are usually clearly visible to the naked eye.

White spot is a parasite. It lives under the top layer of scales and skin on your fish, eating skin cells and causing minute cellular ruptures. The white spots which result from these ruptures are the basis for the parasite’s name, and are what will eventually kill the host (the fish).

How does it get into my tank?

White spot is usually introduced to a tank along with new, infected fish or plants. It can also break out seemingly without warning in an undisturbed tank.

When this happens, it means that the organism has been present for some time, but has been dormant (hibernating), and that some new stimulus – stress, or a change in water temperature – has caused it to awaken and become active.

The original cell of the organism will attach itself to a host (the weakest, oldest, or sickest fish in the tank), usually in the gill plates or under the scales.

After approximately one week of parasitism, the now-mature organism (mature Ich cells are called trophozoites) detaches from the fish and settles on a new surface: usually, a plant or ornament.
It will then form a capsule around itself (called a cyst) and will remain dormant – at least, outwardly - for about a week. During this period of time, the cell within the capsule is furiously dividing: by the time that those seven days are up, that one cell has become approximately 1,000 new single-celled organisms.
These “daughter cells” will then break loose and swim freely about the tank, attaching themselves to new fish - and beginning the cycle all over again.

White spot is highly contagious and progresses very rapidly. 100% mortality is to be expected unless something is done about it.

What can I do about it?

Prevention is obviously the best cure:

• Make sure you only ever buy healthy fish from a reputable, clean breeder
• Inspect the tank from which your fish originate: does it look to be in clean condition? Are the plants healthy and flourishing? Is the gravel clean of sediment and dust? Is the water warm and well-conditioned?
• Check the fish, too – not just the ones you’re buying, but all the fish in the tank. Watch out for ones that are ‘hiding’ (under rocks and behind ornaments) since this is a classic symptom of an infected fish. Make sure none are displaying those tell-tale white spots
• Thoroughly clean any gravel or ornaments you purchase before placing them in the tank, to make sure any cysts are dislodged
• Quarantine new plants and fish for one week before adding them to your tank
• Never overstock your tank, since it will stress the fish (which is a major contributor to outbreaks of white spot, as well as dictating in part the severity of the outbreak)
• Check your fish regularly for white spots. The earlier you detect it, the less impact the disease will have on your tank.

What if it’s too late for prevention?

If you’ve already got an outbreak in your own tank, relax – it may be a serious illness, but at least it’s easy to cure!

The most common, and user-friendly, method of curing condition is through the use of aquarium salts.

Parasites are less tolerant of salt than fish, so adding extra salt kills off all the Ich organisms with no adverse effects to the fish themselves. Make sure you follow the instructions on the package (aquarium salts should always come with clear instructions), and make sure before using it that you don’t have any salt-intolerant fish in the tank like Neons, Cardinals, Glow-Lights, or scale-less Catfish, which are easily burned by salt.

A second alternative is to use a chemical called malachite green. This is an effective way of treating Ich, but unfortunately the chemical is toxic to humans (as well as most plants and snails, so make sure you remove these before commencing treatment!). Always use gloves when administering this chemical – and, because it’s teratogenic (meaning it harms fetuses), pregnant women should stay well away from it.

All you have to do with malachite green is remove the carbon from the filter, and add the appropriate amount (according to the instructions) to the water of the tank. It usually takes about 4-5 days to kill all the Ich cells – a good rule of thumb is to continue use of it until a couple of days after the last white spot has vanished from the fish. 10 days is typical for use of malachite green: just remember to put the carbon back in the filter to remove any lingering traces of the treatment, and give it one or two more days before putting the snails and plants back in.

UV light is also an effective means of treatment: you can purchase inner-tank filters from the pet store with small UV lights inside them. The light kills the parasites in the capsule stage, before they attach to the host.

The transfer method is time-consuming but effective: you’ll need to move all the fish, daily, into a new tank with clean, warm, conditioned water. It takes about 7 daily transfers (so, a week) for all the parasites to fall behind. The only downside is that the fish (and, often, the aquarist!) get stressed by the process, leaving them more susceptible to other diseases. Fish already affected by white spot will sometimes die during the transfer process because their bodies can’t handle the additional stress.

Recommended Reading

For a complete compendium of information on all the problems that tropical fish are subject to, take a look at Katy’s Tropical Fish – A Complete Guide. You’ll learn how to keep your fish happy, healthy, and beautiful, how to keep your aquarium to professional standards, how to troubleshoot health problems as soon as they occur, and learn valuable insider tips and tricks for keeping your aquarium looking spectacular.

Aquarium Fish: Algae Problems

Algae (pronounced AL-jee) are simple forms of marine plant life. They’re pretty basic: they lack leaves, roots, flowers, seeds, and all the other things we normally associate with plants. The term ‘algae’ is an umbrella phrase that’s used to refer to all forms of marine life that are capable of photosynthesis (converting sunlight into energy), although some forms of algae rely entirely on external supplies of energy (in the form of protein and fish waste in the water) for food.

As far as your tropical fish tank goes, algae is definitely an unwanted visitor – it’s a real eyesore. Of course, certain levels of algae are to be expected; small amounts are inevitable wherever there’s light, nutrients, and water in combination.

However, when levels get high enough to be visible to the naked eye, you’ve got a surplus.Unless you maintain your aquarium regularly, you can pretty much count on regular growths of algae obscuring your fish, making the water smell, and generally detracting from the aesthetic appeal of your tank.

But what is it – and how do you get rid of it?

Well, it depends on the type of algae that you have, since each one needs to be treated in a specific manner. The most common forms of algae to affect tropical fish tanks are:

• brown algae
• green algae
• blue-green algae
• green water

What to do about brown algae:

Brown algae is usually the first to appear in a newly established tank. It’s pretty easy to see: it looks like cloudy brown slime growing along the sides and bottom of your aquarium, as well as clinging onto gravel, rocks, and ornaments.

Limiting the light available won’t make any difference to this type of algae, since it’s perfectly capable of growing at low-lighting levels.

Instead, you need to cut right back on the nutrients available for sustaining its growth – which means feeding your fish less. High protein levels in the tank, derived from fish food, will fuel this algae’s growth.

Even if your fish are eating all the food you give them, this doesn’t mean you’re feeding them the right amount: when it comes to food, fish are natural opportunists, which means they’ll eat everything that’s available regardless of how much you feed them. If they’re overeating, they simply excrete the undigested food – which then floats around in the tank, feeding the algae instead!

Make sure you follow the directions stringently on the fish-food package, to be certain that you’re minimizing nutrient levels appropriately.

In addition to keeping food levels down, make sure you’re maintaining your tank adequately with enough water changes and gravel and filter cleanings.

If brown algae appears in an established aquarium, you’ll need to check the phosphate and nitrate levels, as too much of either will encourage the growth of the algae.

If the problem remains ongoing, you can use algae-eaters. These are bottom-dwelling fish – such as the American-flag fish and the Siamese algae eater - which feed on algae, and are commonly stocked by pet stores and fish traders. They’ll make quick work of your brown algae problem!

What to do about green algae:

Green algae will appear in just about any tank with plenty of light. Fortunately, it’s easy to remove (it doesn’t cling to the glass too much) and most algae-eaters will consume it with gusto.

For green algae, make sure you’re minimizing the protein in the tank, as you would for brown algae. Start by cutting the fish-food back by one quarter, and pay close attention to the appearance of your fish: if their bodies become flat and thin, they’re not eating enough. They should be getting just enough food to remain slightly round-bodied.

Keep your fish tank stocked with plenty of algae-eaters, and the problem should take care of itself (although it bears repeating that a certain amount of algae, particularly green algae, is to be expected).

What to do about blue-green algae:

Blue-green algae is technically not really an algae in the true sense of the word – it’s actually a form of bacteria, called cyanobacteria, which is a type of bacteria capable of photosynthesis. Cyanobacteria is one of the oldest organisms in the world, and is thought to have been around for at least 3.5 billion years!
It looks like a slimy coating in a number of greenish-blue shades, and the wastes it releases can actually be toxic to your fish – another good reason to keep it to a bare minimum.

The good thing about blue-green algae is that it’s easy to remove manually: usually, it forms ‘sheets’ of hanging matter in the water, which can easily be scooped out.

The bad thing about it is that it’s pretty hardy: even after a thorough removal, it’ll usually have returned by the next day.

This algae is usually caused by low levels of nitrates (usually in combination with high levels of phosphate), and an imbalance of bacteria in the water.

How to get rid of this persistent eyesore:

• Block all light for a week, and siphon the dead algae out of the tank each day. Your plants will be feeling pretty sorry for themselves by the seventh day, but they should recover just fine.

• Add new bacteria after every water change. You can purchase bacteria pellets for this express purpose from your pet store and aquarium supply dealer. Ask for bacteria pellets that remove ammonia and excess protein from the water.

• Be stringent with your tank maintenance: keep everything clean, check the filter for clogging, make sure the lights are working adequately (blue-green algae needs light to survive, but good fluorescents are necessary to maintain an adequate balance of bacteria and plant life in the tank).

What to do about green water:

If the water in your tank is green, cloudy, and murky, then you have green water. This is a particular form of free-floating algae which hangs suspended in the water, giving it that characteristic opacity – in some cases, the water becomes so green that the fish are obscured.

It’s usually due to a significant excess of light (usually sunlight, as opposed to too much fluorescent), or a problem with your water quality.

To treat this problem:

• Block all sunlight from reaching your tank for several days to one week. You can do this by draping fabric over your tank, or making sure that all the curtains remain drawn in the room where your aquarium is placed. This is very effective.

• Keep your filter mesh as fine as you can: most generic filters come with pretty coarse mesh, so replace it with a fine-meshed sponge or use a diatomic filter (designed specifically to treat algal problems). Remember to check the filter regularly, or else it’ll get clogged.

General algae prevention tips:

Regular maintenance of your tank is one of the best preventative measures when it comes to algae:

• Change the water regularly
• Clean the aquarium regularly
• Use a UV filter in the tank
• Situate the tank away from direct sunlight
• Don’t overcrowd the fish
• Keep the food levels down
• Minimize aeration unless your aquarium is very well stocked: keep airstones and vents to a minimum
• Utilize your plants’ nitrate and phosphate absorbing capacity: stock your aquarium with plenty of fast-growing species like Ambulia and Egeria

Maintaining a healthy, attractive aquarium can be a pretty complex task – there’s so much to keep track of!
For smart, relevant, detailed, and easy to follow advice on keeping a professional-standard aquarium, we recommend  Katy’s Tropical Fish – A Complete Guide.

It’s packed with valuable insider tips for keeping a fabulous aquarium, regardless of budget and experience – all aspects of tropical aquarium maintenance are covered, from fish health to algae problems to fish compatibility. It’s a complete owner’s manual!