ARTICLES FROM RYEDALE REPORTER

THE SWAN MUSSEL

By Majid Ali

Of the several species of freshwater Mussel native to the British Isles the Swan Mussel is the most commonly sold in aquatic retail outlets.

These molluscs are not easy to keep, since they are filter feeders. Personally I would not recommend that they be kept in indoor aquaria, as they have a better chance of survival in large outdoor ponds that have plenty of natural wildlife and organisms such as frog spawn, daphnia and plant remnants harbouring various bugs etc.

In nature these molluscs live in and around mud on the pond floor were they feed on very small particles of decaying vegetation and small live foods. Their method of feeding is by passing food to the mouth on a belt of cilia (tiny flailing whip like processes) driven mucus. An instant siphoning system.

To recreate a muddy pond bottom soil is often used and this does not appear to cause the Mussel any ill effects.

Please note that all such Mussels are sensitive to aquatic medications, in particular those which contain copper.

In aquaria many aquarists', myself included, feed these creatures on commercial liquid foods. This food is best positioned towards the inhalant siphon and the food tube given a good squirt. Liquid food can pollute aquaria so read on for the safe use of this particular food. I make use of infusoria produced by Apple Snails as a supplementary food source for Swan Mussels. The method works as follows:-

1. Acquire several Apple Snails and feed these Snails regularly until their tank is full of infusoria.

2. Remove the Mussel from its aquaria and place into a feeding tank.

3. Squirt a lot of liquid food into this feeding tank. Scoop out a couple of pints of water from the Snail aquaria and add this as well. Leave the Mussel, for several hours, in this tank to feed. Please note that ample aeration is required.

4. This procedure should take place 3 to 4 times a week, in order to keep the Mussel well fed thus in good health.

A friend of mine checks that this method is working, and if the Mussels are gaining weight, by weighing the Mussels once a month.

Did you know? - The Swan Mussel is known to science as Anodonta cygnea.

As part of their life cycle Swan Mussels produce, in spring, a parasitic larvae known as Glochidia, which attach themselves to fish. Glochidia are, in fact, baby Mussels. After an attachment is made a cyst is formed that feeds off the body mucus of the host fish. To be honest they do very little harm (do you know different?) and, usually, drop off within a few weeks going on to develop into adult Mussels.

Did you know? - These molluscs can grow to a size of 15cm and live for 12 years (usually much less in aquaria/ponds).

What is the main purpose of keepng Swan Mussels in aquaria? To act as a breeding station for both the European and Chinese species of Bitterling (please note that a licence, available fom MAFF, may be needed for keeping certain Bitterling species) found in our hobby. As this breeding process is well documented we will just mention that, while acting as a temporary home for these eggs, the Mussel keeps the fish eggs well oxygenated by passing a constant flow of water, through use of its gills, over them.

We conclude our article with a WARNING. Swan Mussels can die very quickly and without warning. They very quickly (as happens with L number Loricarins and Borneo Suckers) pollute the aquarium/pond water so keep watching, and weighing, these particular creatures.

FISH FACT FILE - THE CLIMBING PERCH

Text by David Marshall

Photograph by (and copyright of ) David Armitage

Scientific Name - Anabas testudineus

Scientific Confusion? - With several slight colour and morphological differences in Climbing Perch found throughout their natural range it may well be that, in future, we will see some of these given alternative scientific names.

Natural Range - Thailand, Sri Lanka, Malaysia, Taiwan, Indonesia, Southern China, Vietnam, Cambodia, Phillipines.

Size - 10" (25cm).

Danger? - The gill covers are equipped with various spines used as a defensive mechanism and are said to cause pain (if my experience of badly swollen fingers and large blisters caused by the ventral fins of Synodontis species 'Nigeria' is similar to this then such contact is best avoided and only plunging my hand into extremely hot water took this swelling down) if they catch a human hand.

Fin Movers? - These fish are capable of moving from pool to pool by using their pectoral fins, caudal peduncle and gill covers as a means of locomotion. As a means of protection these fish are said to use the cover of darkness in order to move around doing so in-groups and not as individuals.

Origin Of Common Name? - Climbing Perch came about due to a 'myth'. Because certain individuals are said to have been found in tree tops a 'myth' spread that these fish were capable of shinning up tree trunks with ease but science would prove that fish eating birds actually dropped or left catches of this particular fish on tree branches.

Aquarium Conditions - In his Tetra published book Labyrinth Fish - The Bubble-Nest-Builders Anabantid expert Horst Linke recommends that these fish be maintained in aquaria of 70x40x40cm with a temperature of between 20 and 25 C. Linke recommends keeping these fish in a well-planted aquarium. Mr. Kevin Webb feeds these fish upon maggots and large commercial fish food pellets. These fish have a predatory nature so are NOT for the community aquarium. The two Climbing Perch I care for live fairly peacefully alongside large Loricarins, Synodontis pardalis, Sajica Cichlids, Doradids and a Garra species.

Please remember that these are labyrinth fish so leave a gap between the water surface and condensation shield (in order to keep the labyrinth organ working properly) and watch for signs of velvet disease.

Breeding - Sexes told apart by girth, as that of the female is larger (particularly when in spawning condition). Males may be darker in colour and have more of a knife-edged anal fin than females. Use a large aquarium with plenty of floating plants. These fish do not build nests spawning in open water. Unlike their Gourami relatives they do not entwine in a full embrace. Spawning is said to be a very vigorous affair.

Eggs are clear in appearance and rise to the water surface. Once spawning is complete remove the adults, as they are prone to eating their eggs. Any fry which hatch (said to be from day 3 onwards) would be very delicate and require either green water or egg yolk paste as a first food with newly hatched brine shrimp to follow after the first week or so. The fry would be tiny and prone to velvet disease.

References

Labyrinth Fish - The Bubble-Nest-Builders by Horst Linke, Tetra Press.

Labyrinth Fish by Helmut Pinter, Barron's Publishing.

Star Animals Series - See & Discover Fish (English edition) - Elsa editions.

Dr. Axelrod's Mini-Atlas, TFH Publications.

Articles written by our members can also be viewed on the Canadian-based web-site www.aquarticles.com. Here you will find close to 400 articles on everything to do with the aquarium hobby.