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.

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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.

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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

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Problems With Betta Bowls

However, the waters from which they come are warm: the average temperature is 24-30C (75-86F), according to Fishbase.org. This is much higher than the temperature in most people’s houses, especially in the winter. While they will survive in an unheated bowl provided the room is decently warm, housing them like this seems questionable. When kept at lower temperatures, Bettas are less active and are more susceptible to disease.

While Bettas do much better than most fish in low-oxygen conditions, they still suffer from build up of fish wastes when kept in small bowls. Such bowls must be cleaned much more frequently than a tank to prevent build-up: 100% water changes multiple times per week. The long fins of male bettas are susceptible to finrot, and dirty water increases the likelihood of problems.

Some of the objects in which Bettas are kept are too small for any fish. In petstores, they are often kept in hand-size bowls, or worse, in plastic drinking cups. I’ve even seen a few in containers narrower than their body was long, not counting the fins. Moral sentiment and the fish’s health aside, this is not a sensible way to sell these fish, as they cannot display properly and their beauty is completely invisible.

Advantages of a Heated Aquarium

Keeping these fish in an adequate-sized and warm tank has advantages to the fishkeeper in addition to feeling good about the way you keep your fish. Healthy fish display more, build bubble nests and check every nook and cranny of the aquarium for missed food. They are much more interesting to watch, and a betta doing an aggressive display in a well-lighted aquarium is a truly stunning sight.

Sources:

Fishbase.org

RandomWiktor. Tiny Mud Puddles and Other Lies: Myths and Misconceptions About Our Beloved Bettas

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It has been introduced to Indonesia (Sulawesi), the USA, Hong Kong, Taiwan, China, UK, Papua New Guinea, Guam, Taiwan, Thailand, and possibly the Philippines. This species has been nominated as one of the world’s top 100 invasive species. The method of invasion involves escapees from the pet trade as well as aquaculture. It is illegal to keep this fish in some countries, as well as in many US states.

Very cold water kills Walking Catfish, so if your area goes below freezing in the winter this fish should not become invasive even if some manage to escape. In many areas with warmer water it is often illegal to keep them without a permit. Even if they are legal in a warmer area, it is still very important not to let them escape from their tank.  Because of their ability to walk on land, the possibility of escape is much greater than with most tropical fish.  Make sure their aquarium has a strong and tightly fitting lid so that they cannot push it up and wander off.

Sources:

Global invasive species database. Compiled by Invasive Species Specialist Group (ISSG)

Brogan, Christine. 2003 Introduced Species Summary Project

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Catfish leaps upward
Hovering in mid-water
Hoping for some food.

The Betta

The betta dances
Before the glass’s mirror
Rival dances back.

The Neon Tetra

Swimming together
To confuse bigger fishes
They sparkle with light.

The Guppy

Tail streaming behind
The small fish wiggles onward
Looking for a mate.

The Goldfish

Slow and yet graceful
They sail on through the water
Each alone yet not.

Note: Next week’s post will be a proper article.

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Sources:

Butler, Rhett A. 1999-2008. Mongabay.com – San Francisco, CA

Practical fish keeping http://www.practicalfishkeeping.co.uk/pfk/pages/home.php

Mills, D. 1987 Illustrated Guide to Aquarium Fishes. Galaxy Press, England

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They will happily eat sinking tablet foods. There are several different types of these which can be found at most pet stores. They also enjoy frozen foods, especially frozen blood worms. Live worm-type foods are eagerly accepted so long as they are small enough for the fish to eat.

Types of Corydoras

There is an astonishing number of Corydoras species. The number of named Corydoras species was 156 in 2006 (Fuller, 2006), with new species being discovered faster than they could be named. These fish originally come from South America, mainly from the great river basins of the Amazon, the Orinoco and the Rio Negro.

The most common Corydoras species in the tropical fish hobby is the Bronze Corydoras, Corydoras aeneus, followed by the Peppered Corydoras, Corydoras paleatus, but there are many are other species available. They range in size from scarcely over an inch in the case of Corydoras hastatus, pygmaeus, and habrosus to approximately 3 inches for Corydoras aeneus and others. Fish that look like Corydoras but are larger are probably in one of the genera Brochis or Schleromystax, both of which are closely related to the genus Corydoras. The common Corydoras are usually between two and three inches in size with Corydoras aeneus being approximately three inches when adult.

With so many species, there are many different color patterns available. Most Corydoras patterns contain contrast in dark and light coloring, or large amounts of gray. Different color patterns will appeal to different people, but the intricate pattern of spots on Corydoras trilineatus makes it one of the most beautiful species.

Corydoras Behaviour

Corydoras school. Almost all species are bottom dwellers and enjoy digging in the gravel. The schools often sit on the bottom or hover and swim just above it. The exceptions are the dwarf species which will often be found schooling in mid-water as well as near the bottom. These smallest corydoras have a slightly different and more streamlined shape when compared to the Bronze Corydoras. The shape of these small Corydoras is probably due to their preference for mid-water swimming where a more streamlined shape is useful.

Corydoras can absorb oxygen from air taken into the gut and for this reason will sometimes dart to the surface for a breath of air and then back down to the bottom. This is normal behavior, but if all your Corydoras are doing this constantly then there may be inadequate dissolved oxygen in your tank.

I have kept Corydoras for many years and I have never seen recognisable aggressive behavior by Corydoras against members of their own species or any other, including towards much smaller individuals that have beaten them to the food, and partially grown fry of other fish species.

Corydoras are egg-depositors and will lay eggs on any available flat surface including the walls of the tank, the tank heater, and tank decorations. Reports on whether they eat their eggs are mixed so you may wish to separate the eggs from the adults.

With their even temperament, myriad species, and comical appearance, Corydoras are much more than just tank scavengers. When given what they need to flourish they are a fascinating and beautiful addition to the tank.

References:

Fuller, I. 2006 Starting with Corydoras. http://www.scotcat.com/articles/article33.htm

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Some of these species are sometimes illegally wild-caught and exported from their countries of origin; just because it is on this list is not a recommendation for keeping it.

Enormous Tropical Aquarium Fishes (Over 16 in.)

Red Tail Catfish: Phractocephalus hemioliopterus
Arapaima, Pirarucu: Arapaima gigas (potentially to 16 ft. usually less)
Arowana: Osteoglossum bicirrosum, Osteoglossum vandelli
Black Arowana: Osteoglossum ferreirai
Asian Arowana/Green Arowana: Scleropages formosus
Australian Arowana: Scleropages jardini
African Arowana: Heterotis niloticus
Tiger Shovelnose Catfish: Pseudoplatystoma fasciatum
Shovelnose Catfish: Sorubim lima
Reticulated Pimelodid: Perrunichthys perruno
Plecostamus, Pleco, Suckermouth Catfish: Hypostomus plecostomus
Snow King Plecostomus: Liposarcus anisitsi
Blue-eyed Panaque, Blue-eyed Plecostamus: Panaque suttoni
Sailfin Plecostamus: Pterygoplichthys gibbiceps
Walking Catfish, Albino clarias: Clarias batrachus
Fire Eel: Mastacembelus erythrotaenia
Ornate bichir: Polypterus ornatipinnis
Knife Fish; Featherback: Notopterus chitala
Mozambique Mouthbrooder: Oreochromis mossambicus
Gourami: Osphronemus goramy
Black Shark: Labeo chrysophekadion

Sources:

Butler, Rhett A. 1999-2008. Mongabay.com – San Francisco, CA

Practical fish keeping http://www.practicalfishkeeping.co.uk/pfk/pages/home.php

Mills, D. 1987 Illustrated Guide to Aquarium Fishes. Galaxy Press, England

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My first male and female began courting the evening I took them home from the pet shop. They began spawning the following morning, and did so frequently after this. The male was extremely assiduous in courting the female, and would not stop chasing her around the tank. I went back and bought a second female in order to give the first some peace, and then started adding other fish species to the tank. Fry did not survive in the community tank.

In order to raise fry, I moved the cherry barbs to a 5 gallon tank containing Java moss and Java ferns. I did not succeed in raising any fry from the first spawnings due to an inadequate food supply. It was the middle of winter; all green water sources were frozen and I could not buy any food aimed at egglayer fry in the local pet store. When I tried again later, the weather had warmed and I had also taken to creating green water indoors which gave me a food source for the young fish. I only succeeded in raising one fish the first time, but the fish was a healthy female. I believe the scarcity of offspring in this case may have been due to a poor spawning.

I later left the three fish together in the 5 gallon tank. I had not intended to raise any offspring, but when I looked inside a jar of dirty fish tank water I was about to pour on my houseplants I discovered a young fish swimming inside. I then moved the adults to the main tank and proceeded to add green water 2 to 3 times a day to the little tank, graduating to egg yolks squished through nylon stocking and crushed flake food as the fry grew. Some 40 or so young fish from that spawning survived.

While cherry barbs have a reputation for being shy and rather timid fish, I found that this was untrue of the male so long as there were both females and hiding places around. Under these circumstances the male spent the majority of his time displaying and chasing the females. He was in fact the most aggressive fish in the tank, chasing my neon tetras and occasionally attempting to chase the corydoras catfish which were larger than he was. They ignored him, but his harassment of the female Cherry barbs appeared to cause them stress. One developed a fungus patch on her side which disappeared after I separated her from the male, and one female jumped out of the 5 gallon tank with fatal results. I believe she did this in an attempt to escape the male’s attentions, and any future breeding of cherry barbs will be done with a cover on the tank.

The male’s aggressiveness in this regard severely surprised me as nothing I had read about this species suggested this level of aggression. It is notable that his aggressiveness only occurred when females were present; in the absence of females he usually hid in the darker corners of the tank.

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