The other reason these crayfish are banned in Britain is because they can carry disease which could harm the native crayfish. Unfortunately, there are crayfish being sold illegally in Britain including the Mexican Orange Dwarf Crayfish, Cambarellus patzcuarensis. For more information on this issue, please see Practical Fish Keeping. It is still a problem.

Please only buy species legal in your area, and don’t release any pet fish or invertebrate into the wild.

Koi

Koi are definitely the kings of the pond. They are meant to be viewed from above, and the spectacular colors they come in are designed with this in mind. They are a selectively bred form of the Asian Carp and German Carp. Koi are found in red, white, yellow, gold, orange, silver, greyish-blue, black and lots of combinations of these colors. Some Koi have long fins, but most do not. Whatever their color scheme, Koi are very elegant-looking fish.

The keys to keeping Koi are a large enough pond and good filtration. They are only suited for ponds of 1000gal or
more because they grow over three feet long. They can reach two feet in only three years, which means that you need to have the space they’ll need available now, not ten years from now. They are gentle fish, and can be taught to take food from your hand. They will not harm small Koi or Goldfish, although fancy Goldfish may have difficulty getting their share of the food when competing with Koi.

Koi are very cold-hardy fish, and so long as a small area of the surface remains unfrozen for gas exchange and the water is three feet deep with water of 34F or higher for them to be dormant in they should be fine. This is good, because you are unlikely to be able to house multiple three foot long fish in your house over the winter.

Koi vary widely in price. Ordinary young Koi can be acquired for as little as $10, while a prize-winning Koi could set you back over $100,000. Of all the pond fish, these truly are king.

Goldfish

Like Koi, Goldfish are very cold-hardy. Fortunately, Goldfish only grow to about 12 inches, usually somewhat less. This means they are suitable for much smaller ponds than koi are.

They still need the pond to have an area of two feet or deeper for winter dormancy and to hide from predators.

Goldfish come in many varieties. The most common variety is the Common Goldfish, but there are also dozens of more fancy varieties. Generally, the more fancy the variety, the harder the time it will have in a pond. Goldfish without dorsal fins or with very small double tail fins swim slowly and have more difficulty escaping from predators. They will also have a harder time competing for food with less oddly-shaped goldfish or koi. Bubble-eyes and Celestials are vulnerable to eye injuries. Goldfish like these are better suited to aquariums or indoor ponds in houses without pets that are likely to play predator.

Goldfish such as Common Goldfish, Shubunkins, and Comets are more able to take care of themselves in pond situations and are better choices for your outdoor pond. Double-tailed varieties with dorsal fins such as telescope eyes, fantails and orandas fall somewhere in between. One advantage of buying Common Goldfish or Comets, many of which are actually Common Goldfish, is that they are usually the cheapest goldfish to buy, so if you have an unusually hard winter or get visited by a heron you haven’t lost large amounts of money as well as your pets.

Protection against predators:

Whatever type of fish you have, protecting them against predators is important if you want to keep them in your pond.

-Create a 2ft or deeper area in the pond.
-Submerged and floating plants provide hiding places.
-Install a heron decoy – remove during the breeding season or it can attract rather than repel herons.
-Use milk crates as support for marginal plants – they double as hiding spots for small fish.
-Use a floating decoy fish – when a predator attacks it, the real fish can flee.
-Buy dull-colored fish – there’s a reason most wild fish don’t have bright orange backs.

Other Considerations:

Before you buy any pond fish, remember that you must not introduce them into wild ponds or anywhere they might be able to get into natural waters.

Rosy Red Minnow, Fathead Minnow

This fish’s ideal temperatures are 10-21C, but it can survive much lower temperatures. The Fathead Minnow overwinters in Canadian boreal lakes. That said, it tends to have a high winterkill. Rosy Red Minnows grow approximately four inches in length. They are naturally greenish, but there is a very pretty pinkish-gold variety, which is why they have two names. You may be able to find this fish in your local aquarium store, possibly as feeder fish.

The Rosy Red Minnow can be a source of enteric red mouth disease for native european fish. Therefore, they should not be allowed to let them come in contact with each other.

Golden Orfe

The Golden Orfe grows to approximately 18 inches in length. While Golden Orfe are very pretty fish, they need to be kept in a school of at least three. They are also fussier about water quality than Goldfish or Koi, which is probably why they are less often kept than either Koi or Goldfish.

White Cloud Mountain Minnow

White Cloud Mountain Minnows only grow to 1.75 inches or less, making them the smallest of the fish discussed here. This fish is somewhat more sensitive to cold than other fish discussed here. It can survive down to 5C. Fortunately, their small size means that they can be moved into an aquarium for the winter without the sort of problems you would have doing the same thing with a large species like Koi.

The White Cloud Mountain Minnow is native to streams and prefers clean, well oxygenated water. It would probably make an excellent inhabitants for ponds with a waterfall or streamlike section, or for fountains.

Mosquito Fish (Gambusia affinis and G. holbrooki)

The Mosquito Fish is an interesting fish for very small ponds. It grows to 2.8 inches or less, and is more resistant to extreme temperatures of between 1.5-35C as well as to low dissolved oxygen. Of the two species, G. affinis is slightly more adapted to cold and holbrooki to heat. However, temperature tolerance varies depending on the population and its specific adaptations. Winter mortality of Gambusia tends to be high. Gambusia are closely related to the guppy, and are livebearers. They are probably most useful for very small ponds where the water can get very warm, such as container water gardens.

One problem to bear in mind with Gambusia especially is that they have a history of being an invasive species. This means that you must be even more careful never to allow them near natural water bodies.

Other Considerations

Before you buy any pond fish, remember that you must not introduce them into wild ponds or anywhere they might be able to get into natural waters. Some of the above fish, especially Mosquito Fish and White Cloud Mountain Minnows, are a bit too good at adapting to natural waters. The Mosquito Fish has been the cause of native fishes in New Zealand having local populations eliminated, and it is also a threat to native dragonflies and other aquatic invertebrates. They are also illegal in some areas. Check the legality of owning fish such as Gambusia or WC Mountain Minnows before introducing them to your man-made pond.

Adult Tropical Hobbyist with a Single Tank.
One of the most common situations. Snoop around a little to see what equipment they have. Equipment they might need:
-pH/ammonia/nitrite test kits. These save fish lives, but too many people don’t buy them.
-spare heater
-fluorescent light bulb of correct size and shape. These do burn out.
-fluorescent light hood. Vastly better than incandescent.
-filter inserts for their particular filter
-frozen fish food
-aquarium salt. Useful medication for several diseases, and really cheap. Also good for a few species to have permenantly in their water.
-aquarium thermometer. Essential and extremely cheap.
-hospital/quarantine tank. 5 gal tank with heater and mechanical filter. It is really, really useful to be able to quarantine sick or newly acquired fish. Second hand tanks are a good way to find these cheap.
-general aquarium book

Child with A Single Small Unheated Aquarium
-fish tank decorations. Many children adore these and they are really easy to find in any petstore. They are often among the cheapest fishtank related gifts.
-a ten gallon kit. If the child shows real interest in their aquarium, get them decent equipment. A lot of the little plastic kits are nearly junk. If a plastick kit has goldfish in them, goldfish that live more than a year or so will outgrow the tank.
-a small filter. Many of these tanks don’t come with them and it really improves tank conditions and the ease of keeping fish.
-LED tank light. Looks pretty, uses little energy and now you can grow low-light live plants.

Adult with Single Cold Water Tank
-pH/ammonia/nitrite test kits. These save fish lives, but too many people don’t buy them.
-fluorescent light bulb of correct size and shape. These do burn out.
-fluorescent light hood. Vastly better than incandescent.
-filter inserts for their particular filter
-frozen fish food
-Aquarium salt. Useful for treatment of some diseases and very cheap.
-hospital/quarantine tank. 5 gal tank with mechanical filter. It is really, really useful to be able to quarantine sick or newly acquired fish. Second hand tanks are a good way to find these cheap.
-general aquarium book

The best gift here is probably a 10 gallon aquarium kit.  These usually come with everything required (though they often lack a heater) and are much better value for money than buying everything new separately.  Ten gallons is large enough to have a decent choice of species, yet small enough to keep costs down and be easy to find space for.   Five gallon kits are cheaper but they are much more restricted in terms of what you can keep in them.  If you have the money, 20 gallon kits allow a wider choice of species and decor, as well as increased stability in tank conditions which may make fishkeeping a little easier.

If you are short of money, check the web for second hand equipment.  Be careful to look over what you are buying carefully.  Remember that because it’s second hand, some of it may well be mismatched, missing or not work.  You may well end up buying the problem items new and this can raise the costs above what you initially estimated.  Been there, done that.  Even so, it can still be a lot cheaper than buying new.

Many people buy plastic kits that are cheaper than glass.  These are not such a good idea for a couple of reasons.  Most of these kits lack lighting, they scratch more easily and so don’t last as well, they don’t come with heaters, many heaters aren’t safe for use in them, and they may also lack a filter.  Many of them are also too small for anything other than a Betta or some shrimp.  If your budget is limited, I recommend second hand glass aquaria over these.

Another excellent gift is a book on aquarium keeping.  There’s a lot to aquarium keeping and having a decent book constantly on hand is a good way to prevent mishaps and respond to emergencies.

If the person you are buying for isn’t yet ready for fish, or isn’t sure that an aquarium is right for them, a book can give them a good idea of whether it is what they really want, and what type of aquarium would be best for them.

Don’ts when buying for new fishkeepers:

-Don’t buy the fish at the same time as the tank.  Get them after the aquarium has been set up for two weeks with plants in it, or fully cycled by another method.

-Don’t buy a goldfish bowl for a goldfish.  Goldfish bowls are far too small for a large, waste-producing fish like a goldfish.

-Don’t buy live animals immediately before Christmas.  The stores will be insanely busy and the salespeople won’t have time to help you as much as they normally would.  In bad cases, the animals may also not be as well looked after because the staff get overwhelmed.  Buy the tank, then go back and buy fish once the tank is set up and cycled.

-Don’t buy any pet you aren’t sure they want.

Here are some suggestions for groups of fishes that are compatible inhabitants for 5 gallon tanks.  I have only included fish is that are at least relatively easy to keep.

Note: I am assuming a standard 5 gallon long tank. If your 5 gallon tank is tall and narrow, it will support fewer fish as it is surface area that determines the number of fish you can have. There are a variety of rules of thumb people use for determining number of fish. For a properly-filtered tank of standard proportions containing tropical species, a 5 gallon tank should contain no more than 10 inches of fish. I have kept the fish inches here to 8.5 or less because this leaves more room for equipment malfunction such as short power outages and human error.

Cold water fish need more space – no more than one inch of fish per gallon in a standard-sized tank.

The tanks:
5 gallon tank with plants and a pH of between 6 to 7.

Fish Tank One: Amazon Nano Aquarium 1
6 Neon Tetras
1 Otocinclus

Fish Tank Two: Amazon Nano Aquarium 2
6 Black Phantom Tetras

Fish Tank Three: Betta Bachelor Pad
1 male Betta

Fish Tank Four: Lady Betta and Frogs
1 female betta
2 dwarf frogs
1 Otocinclus

5 gallon tank with a pH of 6.5 to 7.5

Fish Tank Five: Subtropical Stream
4-5 White Cloud Mountain Minnows

Fish Tank Six: Mini Catfish Tank
6 Pygmy Corydoras
1 Otocinlus

5 gallon tank with plants and a pH of 7.0  to 7.6

Fish Tank Seven: Where’s the Fish?
8 shrimp of any mix of species that doesn’t exceed one inch, Cherry shrimp is a good beginner species
1 horned nerite snail

Fish Tank Eight: Guppies, Guppies, Guppies
5 Male Guppies
1 horned nerite snail

This is important for the fishkeeping hobby because a surprising number of fishes are still wild-caught from the Amazon, including such popular fish as Cardinal Tetras. This is not the only major recent drought. There was another large drought in 2005 described as a once in a century drought, and repeated droughts of this nature can hardly help but cause damage to the forest and its fish.

Given the predicted effects of climate change on the Amazon I was expecting something like this to happen. This year’s drought is probably partly caused by El Nino, but previous El Ninos didn’t cause this much devastation, and I blame the difference on climate change. See my previous post on the subject. However, I wasn’t expecting it this soon. There is more detail on the 2010 drought in this article by Heiko Bleher in Practical Fishkeeping: The Greatest Amazon River disaster in history.

Given the major problems aquarium fish in the Amazon are facing, you may wish to avoid buying wild-caught Amazonian fishes for the next year or so, unless you intend to breed them and have the skills to do so.

Small Corydoras Species:

C. osteocarus 1.8in
C. tukano 1.8in
C. melini 1.8in
C. breei 1.8in
C. boesemani 1.8in
C. bicolor 1.8in
C. sanchesi 1.6in
C. paragua 1.6in
C. ortegai 1.6in
C. multimaculatus 1.6in
C. gracilis 1.6in
C. lamberti 1.5in
C. paucerna 1.4in
C. habrosus 1.4in
C. cochui 1.4in
C. pygmaeus 1.3in
C. hastatus 1.3in

Sources:

Planet Catfish for species lengths.

Because they come from running water, they require well-aerated water. This means they should have a filter or at least an air stone, and may well enjoy filtration that produces a strong current.

Crayfish are good at escaping, and tanks for them should have a tight-fitting lid that they cannot get out of.  They typically get to the top of the tank by climbing up any equipment that extends to the top of or out of the tank. Hiding places are important in order to make the crayfish feel secure, and there should be more hiding places than crayfish in a given tank in order to reduce fighting.  Crayfish like to burrow and will rearrange tank decorations if the decorations are light enough. They also eats live plants, so try not to get too attached to any decorating scheme or plant you put in their aquarium.

They are are best kept one to a tank, as they are likely to fight with each other. Some may also be kept in male-female pairs, which is necessary if you want to breed them.  There are also a couple of very small species in the genus Cambarellus that can be kept in groups if sufficient hiding places are given. Like Bettas, crayfish are sometimes used in animal behavior labs to demonstrate aggressive behavior – in both species the animals cannot actually get at each other.  The behaviors are observed as they threaten each other through the glass.

Crayfish are larger than most other invertebrates commonly kept in aquaria and large adults will need considerable space.  Ten gallons is enough for an adult of most of the North American species, but some of the Australian species can reach 16 inches and would need a 30 gallon or larger tank. There are a few dwarf species such as the Dwarf Cajun Crayfish, and Mexican Orange Dwarf Crayfish, that can be kept in a smaller fish tank or in a group in a 10 gallon tank if there are enough hiding places.

Crayfish will eat fish if the fish are small enough, so tank mates need to be considered very carefully.  Slow-moving species of fish are likely to get their fins damaged even if they do not get caught. The dwarf crayfish species can be kept with fish, but keeping them with very tiny fish or fry is probably not safe, and they should not be kept with large fish because the fish may eat them.

Crayfish can be fed on shrimp pellets or flakes, but there are often specialty crayfish foods available and many crayfish enjoy vegetables such as zucchini or peas.  If you live in a soft water area, you may wish to add calcium to their water, as this nutrient is important for growing a healthy exoskeleton.  Molting crayfish will eat their discarded exoskeleton to recover the nutrients, so this is often left in the tank.  Temperature requirements vary, but many species are happier in cooler water than the standard tropical tank.

Some Interesting Crayfish Species:

Procambarus alleni “electric blue”, Florida blue lobster
6-8 in, typical needs for a crayfish.

Procambarus sp. “Marble”
This species has no males.  The offspring are clones of the parent. More mundanely, it grows to about 4 inches in length and has typical requirements.

Cambarellus patzcuarensis Mexican orange dwarf crayfish
Thi species is tiny, at 1 to 1 1/2 inches in length.  If it can be kept was small fish, but not with large fish as the fish may eat this crayfish.  Many individuals can be kept in the 10 gallon tank so long as there are hiding places. It can stand warmer water, being comfortable in 60-82F.

Cambarellus schufeldtii Dwarf Cajun Crayfish
Very similar to the Mexican Orange Dwarf.

Cherax tenuimanus “Blue Marron”
This species grows large at 10 to 16 inches in length and requires a larger tank of 20 to 30 gallons.  It likes temperatures of 60 to 72 Fahrenheit, and care is otherwise as for most crayfish.

Sources:

Aquatic Community Aquarium Forum

canadiancrayfish.ca

McClure, Susan. Crayfish Care. Badman’s Tropical Fish.

Unfortunately, it is also illegally wild caught in various places in Southeast Asia. Captive breeding, poaching, and smuggling are all encouraged by the high prices these fish bring.

Captive bred fish from Singapore usually come with an embedded microchip to prove that they are captive bred and prevent theft. Asian Arawanas are selectively bred for color, especially red or gold variations. There is a tradition in China that this fish, especially if red or golden, brings good luck to its owner. This is one reason for the fish’s popularity and high price.

Because of the prices these fish sell for, farming this species is quite lucrative and has been described as a ‘gold rush’ on the Arowana club website. A very good specimen may be worth tens of thousands of dollars.

Because Asian Arawanas are so expensive, they are sometimes smuggled. This means that if you are looking to buy one, you should check its papers and that it has an identifying microchip. It is all too easy to find stories about Arowanas being confiscated by customs officials, whether in boxes under legal items, or inside a dress being worn at the time. Problems you just don’t get with Neon Tetras…

Sources:

Arowana-care.com

Arowanaclub.com

CITES Convention Text

Fishbase.org

Ng, P., Tan, H. (1997) Freshwater fishes of Southeast Asia: potential for the fish trade and conservation issues. Aquarium Sciences and Conservation. Vol 1: 79-90

UNEP-WCMC. 6 March, 2007. UNEP-WCMC Species Database: CITES-Listed Species