Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Difficult species

Arapaima, Arapaima gigas
Arapaima, Arapaima gigas

Make sure you can care for what you buy

You can help protect yourself from very difficult problems by learning about the fish BEFORE you buy it and by making sure that you can cope with all of its needs when it has become an adult, if you break either of those two basically commonsense rules then that makes you part of the problem.

We aren't saying that you should never buy these fish listed on this page, we are saying that all the fish listed need expert or specialist care in some way or another and if you buy them and don't offer that level of care then the animal involved will end up dying very prematurely and the hobby as a whole is brought into disrepute which in turn gives ammunition to the people who would like to an end to keeping fish in aquariums.

As you read through the following list you will notice a common trend of the animals on this list slowly starving to death. Some of the animals will seem to be feeding but still slowly loose weight and perish within a few months of captivity because they aren’t getting the proper diet they require. It would be similar to us trying to live off of nothing but chocolate bars, although we are getting energy from it our body needs a lot more.

Specialist or obligate feeders can’t be forced to accept a varied diet and survive as long as the would if they had the proper diet. Same with carnivores, although they will pick at algae or nori that is mixed with other foods, they will derive no nutritional benefits from it. Algae eaters require algae to survive, it’s what their system is designed for, feeding them only meaty foods can be harmful to their system and will drastically shorten their lifespan.

Although most of these animals are commonly available please think twice before buying one, ask yourself if you can genuinely meet all of its needs for the rest of its life. If you are unsure then leave it where it is. There is no pleasure in keeping an animal only to watch it slowly deteriorate and die prematurely.

Arapaima, Arapaima gigas

Growing to an astonishing 15 feet in length, Arapaima are very unsuitable for home aquaria. Unfortunately these monster sized fish are sold as juveniles to unsuspecting aquarists who don't do their research or people who think that they can defeat the odds and eventually have a tank big enough for them.

Even if they are housed in an adequately sized tank they wont grow to their maximum size while in captivity. However, they will out grow pretty much any home aquarium, if they live long enough. To make maters worse, they have fairly rigid, inflexible bodies. This makes it hard for Arapaima to turn around so the tank it's going to be housed in needs a minimum of twice it's body length at the narrowest point. Most die well before reaching their full potential because they are housed in inadequate conditions. Fortunately their sale is becoming more and more restricted since they have been put on the CITES list.

Chocolate gourami, Sphaerichthys osphromenoides osphromenoides
Chocolate Gourami, Sphaerichthys osphromenoides osphromenoides

Chocolate Gourami, Sphaerichthys osphromenoides

Chocolate Gouramis are one of the most sensitive freshwater fish commonly available for sale. Chocolate gouramis are extremely intolerant to changes in water chemistry, even small water changes can stress them beyond endurance if the water parameters are off so small daily changes are recommended rather then larger weekly changes. Most Chocolate Gouramis won't accept flake or any other prepared food at first and so must be fed a diet of suitably sized live food. Some can be weaned on to frozen food with a little patience and some will even learn to accept flake food. They will thrive best in a lightly stocked well planted aquarium either with just their own kind or with some other small, gentle and slow moving fish.

Freshwater Stingrays, Potamotrygon sp
Freshwater Stingrays, Potamotrygon sp.

Freshwater Stingrays, Potamotrygon sp.

Freshwater stingrays are bottom dwelling fish that grow to well over 24 inches in diameter. They require a large area for swimming and to accommodate their tails when attempting to turn, this means that they will need a tank at least three times longer and two times wider then their body. Stingrays also need to be able to bury themselves in the substrate as a means to hide from predators and feel secure in their environment. If they are kept in a tank without any substrate they will becomes stressed out very easily.

They are also very sensitive to changes in water chemistry and are very prone to bacterial infections in less than perfect water. Their sting poses a very serious threat and the fish needs treating with great respect.

Pangasius .sp
Pangasius .sp

Pangasius sanitwongsei and P. hypophthalmus (formerly sutchi).

All grow to big to be kept in an home aquarium at around 6.5 ft and 4 ft respectively. They are best left in the wild where they belong, in the home aquarium they face a certain, premature and utterly pointless death.

Red Tailed Catfish, Phractocephalus hemioliopterus
Red Tailed Catfish, Phractocephalus hemioliopterus

Red Tailed Catfish, Phractocephalus hemioliopterus

These massive bottom dwelling fish can easily grow over 4 feet in length. The red tailed catfish is commonly available to unsuspecting hobbyists when they are only a few inches long.

Often there is very little warning about the size they get to or how quickly the red tailed catfish can grow. Red tailed catfish also have a very big appetite and will attempt to eat anything and everything in an aquarium so all extra decorations will be considered food. If the Red tailed catfish eats an inappropriate object it can lead to serious internal problems and blockages resulting in its death.

Moorish Idols, Zanclus canescens
Moorish Idols, Zanclus canescens

Moorish Idols, Zanclus canescens

The Moorish Idol is a gorgeous fish by any standards and a very desirable one for any aquarium, or is it? Moorish Idols have a very specializes diet and nothing else is able to replace it. They are also very sensitive to water quality and are one of the first fish to parish at the first sign of infectious disease in the tank. The result, 95 % of captive specimens die within a few months of being caught. None live their natural life span in captivity, they should be left where they are. There is an alternative in the Bannerfish which if given proper care will adapt very well to captivity and is almost identical to the Moorish Idol which makes it even more pointless trying to keep a Moorish Idol

Anemone
Anemone

Anemones

Anemones are extremely demanding mobile animals. They are photosynthetic and require intense lighting in order to survive as well as regular feedings, good water circulation and stable conditions. They are extremely delicate animals and don't heal very well from physical damage. In captivity most Anemones live (at best) for 1/80th of their possible life span. Anemones have a very slow metabolic rate therefore once they show symptoms of stress it is often too late to save them. Their slow metabolism also makes them slow to heal or to die. A problem that occurs in a tank today may take three or four months to show on the anemone.

Blue Ribbon Eel, Rhinomuraenia anboinensis
Blue Ribbon Eel, Rhinomuraenia anboinensis

Blue Ribbon Eel, Rhinomuraenia anboinensis

The Black Ribbon Eel is a juvenile Blue Ribbon Eel and is extremely difficult to get to feed in a captive environment. The Black form of the Ribbon Eel denotes that they are juveniles. Unfortunately the juveniles are extremely sensitive to water changes, suffer greatly during transportation, are less likely to eat in captivity and are much more susceptible to diseases then they are after they have matured.

The Blue Ribbon Eel is a matured male of the species and is very sensitive to water chemistry and requires a varied diet. Unfortunately, both the Black and Blue Ribbon Eel generally starve to death in captivity within a couple of months. Near the end of their natural lifecycle, the Blue males will change into a golden female. Females only live long enough to mate once and lay their eggs. Shortly after they lay their eggs the female will die. There have been no recorded cases of anyone being able to keep a Ribbon Eel long enough to mature into a female.

Butterflyfish
Butterflyfish

Butterflyfish- family: Chaetodontidae

Although there may be a exceptions, most butterflyfish aren't really suited to captive life. They are very difficult to feed in captivity and generally starve to death within short order. Their exact dietary requirements are unknown and some are obligate coral feeders. Butterflyfish also have small mouths so the ones that do attempt to eat frozen foods require adequately size food particles that will fit in their mouths. They are extremely poor shippers and the stress of shipping them is often enough to kill them. Butterflyfish are very sensitive to changes in water chemistry and prone to diseases which they seem unable to fight off.

Carnation Coral
Carnation Coral

Carnation Corals - Dendronephthya sp.

Although carnation corals are some of the most vibrantly coloured corals there have been no known successful cases of keeping one alive for any length of time in a captive environment. They are non-photosynthetic deep sea corals that are generally found hanging upside-down underneath ledges in the wild. Their feeding and water flow requirements are completely unknown. Unfortunately most LFS’s realise these corals don’t live very long and are eager to sell them as quickly as possible with little to no warning and at fairly inexpensive prices.

Cleaner Wrasse, Labroides dimidiatus
Cleaner Wrasse, Labroides dimidiatus

Cleaner Wrasse, Labroides dimidiatus

Cleaner Wrasse are imported because of their specialized cleaning services. In the wild they perform the invaluable service of cleaning parasites off of other fish and people want to see this symbiotic relationship in their tanks. However the impact that collecting cleaner wrasse from the reef is great. The fish that rely on their services are more vulnerable to the parasites and disease quickly spreads among reef populations. To make matters worse, cleaner wrasse have one of the poorest survival records in captivity so not only does their capture leave the reef more vulnerable, they are captured only to die needlessly soon afterwards. They are obligate feeders, meaning they can only survive if they have a sustainable amount of parasites to feed off of. Although people claim to have kept them alive more then a few weeks and adapt to eating prepared meals, these cases are very rare and the number of cleaner wrasse that perish because of the false hope people have reading these cases generally goes unreported

Cuttlefish
Cuttlefish
Photo by Wikipedia

Cuttlefish

Cuttlefish are extremely delicate fish that have been only kept alive for a couple weeks in professional care. They are very sensitive to changes in water chemistry and get stressed very easily making them impossible to keep alive for any length of time. Their captive needs are completely unknown.

Feather Sea star
Feather Sea star

Feather Sea stars and Sea lilies, Class Crinoidea

Sea lilies are the oldest living members of the Echinoderms and Feather sea stars evolved shortly afterwards. Even though these primitive echinoderms have been around for millions of years, they are extremely sensitive and delicate animals. Most of the crinoids have very little chance of surviving in an aquarium due to the collection methods and transportation of them causing irreparable damage. Crinoids are filter feeders however their exact dietary requirements are unknown. Many species come from temperate or arctic waters and will quickly die in the tropical temperatures more reef tanks are maintained at.


Flame Scallops - Lima sp

Flame Scallops - Lima sp

Flame Scallops are always a big hit at the LFS, their electric blue flames shooting around the outer edges of their fire red mantel will tempt nearly any fish keeper to want to take them home. Unfortunately, they are extremely difficult to keep alive for any length of time. They are filter feeders however the exact feeding requirements they need are unknown. Flame scallops also have a propensity to hide in a tight corner amongst the rocks in order to feel secure. Unfortunately most hobbyists don't like this idea and promptly move them back out into the open where they can be viewed at leisure. The scallop then expends a lot of energy again trying to find a secure location. This energy expenditure weakens them considerably and since they aren't getting the food they need in an aquarium, they die prematurely.

Jellyfish
Jellyfish

Jellyfishes

Jellyfish have very limited locomotive abilities. As such they require a specially developed tank to accommodate their limitations. If they are placed in a tank with any corners they can get caught in the corner and quickly expend a lot of energy without being able to move anywhere. They also have very delicate flesh that would easily be torn apart if they were to be placed in a tank with a lot of water movement or if they were to get caught in any filters or powerheads. Like all inverts, they are very sensitive to water quality and will quickly perish if the water quality degrades.

Long-nosed Filefish, Oxymonacanthus longirostris
Long-nosed Filefish, Oxymonacanthus longirostris

Long-nosed Filefish, Oxymonacanthus longirostris

Although most filefish can be kept in an aquarium, the one that is most often seen for sale, the Long-nosed Filefish is not suitable at all. It is an obligate feeder and will only survive on a diet of live coral polyps. It may attempt to eater other prepared foods, however the long-nosed filefish will still starve to death if it does have live coral polyps. It is also believed, but not known for certain that other member of the genus Oxymonacanthus are also obligate live coral polyps feeders.

Dragonets
Dragonets

Dragonets - Family: Callionymidae

Although they are extremely popular fish because of their unique colouration and antics they are extremely delicate. Most of them starve to death within the first 3 to 8 months depending on the size of the tank they are kept in. They require live food in the form of copepods and amphipods; very rarely adapt to eating prepared foods. Because of their dependency on live foods a single dragonet can quickly deplete an aquarium of it’s ‘pod population. Of course there are people who insist on trying to keep these fish. The few people who have kept them alive have very large tanks with at least 120 lbs of live rock in a mature tank that is at least 1 year old. They also have built areas of the tank specially designed as a sanctuary for ‘pods to hide, grow and multiply so that the dragonets don’t have the ability to completely deplete the tank of ‘pods. It is also important to keep an eye on the ‘pod population in the tank and introduce new cultures on occasion to maintain a viable population.

Silver arowana
Silver arowana

Silver arowana

Another giant fish often seen for sale is the Silver Arowana. Although they can grow to around 5ft in nature they rarely get that large in captivity, however they are fast growers and do grow much larger then most home aquaria are capable of housing.

In the wild Silver Arowana can feed on insects flying above them and have become very good and powerful jumpers in order to catch their prey. This instinct runs true making them prone to jumping out of their tank if they see any sort of insect flying overhead, so they require a covered aquarium to prevent this.

Nudibranch
Nudibranch

Nudibranchs

These colourful sea slugs are commonly available at most LFS’s, although their popularity is finally starting to dwindle as more and more people realise how unsuited they are to captive life. All nudibranchs are carnivorous and are specialist feeders. (Although the lettuce sea slug looks like and is often called a nudibranch, it belongs to a different family of sea slugs.) Many of them specialize on different types of corals or sponges for their nutrition, which is undesirable and unsustainable in a reef aquarium. It is also unknown what each species of nudibranch feeds upon. To make matters even worse, nudibranchs contain toxins that are released upon death and have the ability to kill most of the life in an aquarium.

octopus
Octopus

Octopi

It is well-known how intelligent octopi are and it is their intelligence that makes them very poor specimens for captive life. Octopi are escape artists that have been known to open lids of tanks, fit through amazingly tiny openings, and even unhook latches. When stressed, Octopi release noxious ink used to blind predators while they make a quick escape to a safer and less polluted area. However, in an aquarium with a very small volume of water compared to nature, this ink quickly pollutes the water, which results in the octopi being poisoned.

Seahorses - Hippocampus sp
Seahorses Hippocampus sp

Seahorses Hippocampus sp.

Although people are able to keep seahorses successfully and have them breed in captivity, they are still extremely delicate fish. They are extremely slow and fussy feeders that very rarely accept prepared foods, especially wild caught specimens. Seahorses require a constant supply of live food such as mysid shrimp.
Because they are such slow feeders it is essential to have a tank dedicated to their care without other fish to steal their food. Even in a dedicated tank with live food available, they can easily starve to death if the tank is too large and they need to search a lot for food.
Wild populations of seahorses are under a lot of strain from illegal collecting for "medicinal" usages and hobby usage. Many countries have started to ban the importation of these fascinating creatures in hopes of protecting the wild populations.

Shrimpfish or Razorfish, Aeoliscus strigatus

Shrimpfish or Razorfish are very delicate plankton eating fish that are best kept in schools. They require large supplies of live plankton sized foods and will often eat amphipods and copepods. Although these may appear abundant in an aquarium, the Shrimpfish will quickly deplete the tank of it's resident population. Even tricks used to attempt to maintain a viable population wont supply enough natural live food to keep them alive for very long. They are also slow feeders and will require ample time to feed so they can't be kept with more aggressive feeders.

Difficult Species

The animals listed in this article are known to be extremely difficult to keep. There are many reasons for this, but size or diet play a very important role. Some fish grow to huge proportions and the average house/hobbyist cannot provide satisfactory accommodation which will allow the animal to grow and behave normally. Red-tailed Catfish can reach 1.5 metres in length keeping an adult in a 20 ft by 10ft heated pond is the same as keeping a Tetra in an aquarium 6ins by 3 ins. But lots of these fish are sold every year as 3 ins babies and we see lots of photos of the young fish being shown off by their new owners, odd then, that we never seem to see any photos taken 12 months later on showing how well the fish is doing!

Most of these fish won't immediately turn belly up but just because one is still swimming after a week in your care doesn't mean it is "happy" or thriving.

Successful fish keeping is measured in years, not days weeks or months.