CONTENTS.                                             SPRING 2008 EDITION                                                                                 

PAGES

1.                                             Society Officers.

2.                                             Society Information.

3.                                             Editorial.

                                                By Stan McMahon.

4.                                             Chairman’s Chatter.

                                                By Julie Rundle.

5.                                             Fish Larvae

                                                By John Rundle.

10.                                           Voyeurs Put Off Their Ideal Mate.

                                                By Nora Schultz.

12.                                           Guppies sexually Harass Threatened Species.

                                                By Billy McNeil.

15.                                          Rollercoaster of Fiskeeping.

By Diana Andrews.

18.                                           Seahorse Protection.

                                                By Neil Garrick – Maidment.

Society Web Site = www.plymouthfishkeeperssociety.co.uk

Cover picture: Assorted Fancy Guppies (Poecilia reticulata).

 EDITORIAL                                                         STAN McMAHON

 “We’ll gather Lilacs in the spring again”! To quote that terribly, terribly spiffing chap, Noel Coward. More like Frankie Howerd they way my garden and pond are behaving this spring. Enough of that. Yes! Welcome to the Spring 2008 Issue of “Fishy News” magazine. We have an interesting magazine for your perusal, with another “tell it like it is” article from Di Andrews on how the hobby has affected her life and times (oh! And Ray’s as well). Just the job Di! I have included a couple of articles relating to fish behaviour, with a rather shocking observation on the brutal sexual strategies of male Guppies. Also news on the conservation legislation to protect the “poor mans’ scampi”, sent to me by Peter Burgess. Final thanks must go to my “article stalwart”, John Rundle with a contribution on Fish Larvae. So I do hope you will enjoy this issue of your magazine.

 I am now looking for more articles for our special 60^th. Anniversary issue to be distributed in June, so we will have to get our skates on to get it out in time. I do intend to include items from all our yesterdays covering the history of our Society over the last 60 years. Some contemporary copy would bring the story right up to date (deadline mid-May so not long). Please, please get something on paper to mark this great milestone Anniversary.

A big thank you to Ted Sparrow for his help and to Andy Cann for all his efforts in getting this issue out in colour and collating it all together. Carol Cann must get a special mention for all her terrific work on our new web site, well done Carol. Big cheers to Sara for the consultation work on the computery bits.

I will sign off with something I think Julie, Andy, John L and Ted will appreciate:

“Never drink alone – always with a friend. That way you’ve always got someone to get you home”. Never a truer word said in jest! Oops might need to get myself out of that one at the bar folks.

Slainte Va until June.

 CHAIR’S CHATTER                                            JULIE RUNDLE

Well here we are in our 60^th year and we are already making great head way on the plans for June in particular. June is the month when the Society was formed and so we are making this a special month in our Diamond anniversary year.

We are planning a celebration dinner at the end of June on the 28^th and I am already getting the feeling that this is going to be a brilliant night. It is going to be good to see many past and present members along with family and friends. I also look forward to meeting members of the FBAS during the month of June.

Having grown up with this Society ever present in my life, it is amazing for me to be now taking part in the 60^th year as Chair of the club. But what is more amazing is that this club is still going strong whilst other clubs fall by the wayside. So that is something to celebrate!

Even though we are celebrating it is not a time to lose sight on continuing to provide a club for the future. We need to keep focused on all aspects of fish keeping and ensure that the Plymouth Fishkeepers’Society can keep going for another 60 years.   

So if you have any ideas or thoughts on things that either we could include, change or improve on in the club then speak up, this is your club. Most of all please support as much as you possibly can in all areas of club life from lectures, table shows and raffles to social gatherings.

Happy anniversary fellow fish keepers.

 FISH LARVAE                                                                      JOHN RUNDLE

Without doubt when breeding fish the most crucial stage is when the larval are first able to free swim on their own accord and the need to find external sources of food.  A couple of factors that often control how difficult it for us as fishkeepers, when attempting to raise a brood of fry, is their minute size and the number of fry in the brood.

In the wild this is governed by natural factors such as, there would be plenty of food around for the fry and there would be plenty of space for large broods of fish and natural reduction by predators.

So we have to:

·         Supply food of correct size

·         Supply food in correct quantity

·         Supply quality food that will promote growth

·         Supply enough space for brood to grow

·         Be prepared to cull any runts in the brood

Over the years through work and the hobby I have bred some strange marine and freshwater aquatic animals ranging from molluscs, crustaceans and fish.  Whose adults were small to quite large and resulting progeny when first born have varied from just a few microns to a few millimetres in length.

When writing about breeding tetras, barbs, danios and rasboras I have mentioned many times in my articles such words as yolk sac larvae and free swimming larvae but what do these terms really mean?

Just the size difference between larvae and adults tells us that they feed on different foods and they use different feeding strategies.

In terms of feeding, fish larvae are without doubt separate species when compared to their adult counterparts.  What is meant by this statement is the larvae after hatching from the egg are so small and poorly developed that their feeding ecology is vastly different from that of what the species practices during the rest of its life.

So special attention must be giving to the way that young fish:

 ·         Search

·         Find

·         Ingest their food.

 In my fish breeding articles I mention the stages of growth of the fish, they are:

·         Yolk sac larvae

·         Free swimming larvae

·         Juvenile

·         Adult

LARVAL PERIOD

There are two distinct periods in the larval period.

THE YOLK SAC PERIOD:  This is when the larvae first hatch and carries its own food supply in the form of energy rich yolk. 

THE LARVAL STAGE:  This is when the yolk sac has been absorbed and before metamorphosis into the juvenile stage.  It is also the point when the fish we are looking at become ‘free swimming’.  Their food source now is exogenous.

 END OF THE LARVAL PERIOD

 This can be best described in terms of a metamorphosis.  The transition from the larval appearance to the time when the small fish takes on the characteristics of the juvenile. 

Some of the charges are:

• Yolk sac resorbs
• Paired fins develops
• Muscles are defined and active

JUVENILE PERIOD

This period begins when the organ systems are fully formed or nearly so.  Juveniles are recognizable by the presence of fully formed fins and have the appearance of miniature adults.  Although they may not often have the distinctive adult colour patterns.

The juvenile period lasts until the gonads become mature and is usually the period of most rapid growth in the life of a fish.

ADULT PERIOD

 Once the gonads are mature a fish can be classed as an adult.  The onset of this period is reflected in spawning behaviour and often in the development of reproductive structures and colour patterns.

Now that we have looked at all but very briefly the stages of life of the fish, we can now look at the practical side of successfully raising a brood of these egglayers in our tanks.

We have looked at the natural steps of larval development, so how can we raise in our tanks broods of barbs, danios, rasboras and tetras from the minute yolk sac larvae to the adult stage.  This is the way that has allowed me to raise, over a long time, thousands of fish. 

 YOLK SAC LARVAE

This a time when you can lose the brood by placing any source of food into the tank, dry foods and live foods such as brine shrimp that will die will pollute the water.  This will subsequently kill the brood that are not able to take an external source of food.  It is also not the time to feed an infusion type food. 

FREE SWIMMING LARVAE

This is the time when we see the still tiny larvae moving through the water on their own accord, swimming in darting motions either near the surface or in mid water.  It is also the time when they are able to external sources of food.

This is a critical time in the life of the young fish, a time when there must be an adequate amount of food and it must be the correct size and quality.

It has been proven that the vision of this type of larvae is poor.  Despite the general excellence of vision in mature fish, that of the offspring is distinctly inferior.  The handicap is probably one of the reasons why fish breed in considerable numbers, given the probability that so few survive. The often transparent bodies of the larva cannot shield the nervous system from light, so that, while their powers of image formation are limited, they respond like plants to light that strikes their bodies and use other senses to find their food. In fact we have to make sure that there is enough food in the correct density and size for it to nigh on flow into the mouth of the free-swimming larvae.  We have a few options for the first feed:

1. A cultured minute live infusion food that has always gone under for general name of “infusoria”.  I have cultured this source of food for years using fresh powdered milk.  (see reference at end of article)
2. I have in the past few years been using a very fine powdered dry food supplied by ZM foods.  This has proved very successful for certain species of danios, barbs and a few tetras.  If fed carefully the foods floats on the surface of the water and the free-swimming larvae seem to sense the food and feed. 
3. Recently I have started culturing vinegar eels Turbatrix aceti they are about 2mm in length and swim in mid water and will stay alive until eaten by the larvae.  

When the larvae have been fed correctly on one or more of these foods for a few days the ‘fry’ as I will now call them should be able to take larger foods such as live brine shrimp nauplli or a larger grade powdered dry food.

Once at this stage the problems should be behind the fish breeder and the fry will move on to the juvenile and adult stage.

SPACE

Fish such as danios, barbs, rasboras and tetras can be prolific breeders and just one pair will produce hundreds of eggs.  If the fish breeder is successful in raising the brood then a fair amount of tank space will be required.  In the wild this is not a problem but we must only keep and raise enough fish that we have space for.  All runts and deformed fish must be culled and if you have too many fish for your tank space then why pass some on to friends.

CONCLUSION

I hope that this brief look at the life history of these egglaying fish will give you an insight to the wonderful biology of our world of fish.

In future articles I hope to look at the methods of feeding in more detail.

References: 

Fishes an Introduction to Ichthyology by Peter B. Moyle & Joseph J. Cech, Jr.

Biology of Fishes by Q. Bone, N. B. Marshall and J. H. S. Blaxter.

Breeding Egglayers by John Rundle

Live Foods for Aquarium Fishes by John Rundle

VOYEURS PUT MALES OFF THEIR IDEAL MATE         NORA SCHULTZ

I found this little snippet of research in the New Scientist and thought you might be interested. Oh yes! Voyeurs don’t put males off Nora Schultz by the way, well not that I know of.

Mating fish don't like an audience, it seems. When another male spies on them they change their mind about which female they prefer. The findings may alter the way we think about mate choice driving evolution, researchers say male Molly fish of the species Poecilia Mexicana normally prefer to mate with large females who produce more eggs. In mate choice experiments, a male will spend 80% of its time near large females and only 20% near smaller ones.

But when Martin Plath at the University of Potsdam in Germany and colleagues stuck a glass container holding another male into the tank to let him watch the show, the first molly changed his mind. Under the gaze of the intruder, he began to pay equal attention to both large and small females.

Being watched by a green swordtail (Xiphophorus hellerii), on the other hand, did not faze the mollies at all – they only slightly reduced their preference for large females.

"We think that the molly does this to avoid sperm competition," Plath told New Scientist. "It's likely that the other male will share the preference for large females, so it makes sense for the molly to not invest all his sperm into one female."

EVOLUTIONARY DRIVER

 Another possible explanation would be that the desire to fight a competitor distracts the very aggressive mollies from their true mate preference, although Plath considers this less likely. "We have just repeated the experiment with a completely non-aggressive group of fish and got the same results," he says.

Peter McGregor at Cornwall College in the UK, who studies communication networks in animals, says the results highlight how sensitive mate choice can be to even subtle interactions between individuals.

"The other male cannot get actively involved and still his passive presence has this dramatic effect", he says.

Previous studies have shown that female guppies – and humans – prefer males that are popular with other females, and that human males adjust their sperm production to perceived competition, but this is the first direct evidence that mate choice can be reversed by an observer.

”Mate preferences are often seen as drivers of evolutionary change," says Plath. "These results show how important it is to consider them in the appropriate social context."

Journal reference: Animal Behaviour (DOI: 10.1016/j.anbehav.2007.05.013)

GUPPIES SEXUALLY HARASS                        BILLY MCNEIL

 THREATENED SPECIES.                                                                    

Here is another snippet from a recent “New Scientist”:

Male Guppies may sexually harass females of another fish species to prevent them from reproducing, researchers suggest. They believe the Guppies – which invaded Mexican rivers and lakes – are using sex as a way of suppressing one native fish population. The researchers also think the Guppies may physically harm the native females so they are unable to reproduce with males of their own species, or shy away from further interactions with males.

Guppies, originally from Trinidad, invaded Mexican waters in the 1950’s. The pet trade is generally blamed for introducing them around the world as aquarium owners wanting to get rid of fish, sometimes dumped them into rivers.

In Mexico and elsewhere, the released guppies rapidly reproduced. "Male guppies are very sexually active," explains Alejandra Valero at the Universidad Nacional Autónoma de Mexico, who led the new study. She says guppies are "like sex machines".

DECLINING SPECIES

 One species that suffered from the invasion of the guppies was Skiffia bilineata, a fish native to Mexican waters which is threatened with extinction. Female skiffia look like female guppies, so Valero and her colleagues wanted to find out if this was contributing to the species' decline.

They put male and female guppies in aquariums with female skiffia and found that no matter how many female guppies were around, male guppies would try to copulate with females of both species.

Their advances were unsuccessful, but Valero and her colleagues believe that the attempts at sex might be harming the female skiffia. If this is true, the skiffia may not be able to go on to reproduce with males of their own species.

The two species have very different ways of reproducing. Skiffia sex is consensual – males have no extending reproductive organ so the only way for their sperm to reach the females' eggs is for the two animals to line up their genital openings.

SEXUAL HARASSMENT

Guppy sex is more violent. Males have a hooked genital organ known as a gonopodium, which they insert into the females. Past research has shown that the gonopodium maims guppy females. It is thought that the resulting inflammation locks the sperm inside the female.

Valero and her colleagues believe that the guppies may attempt to insert their hooked organ into female skiffia and harm them in the process."We see the males draw their gonopodium forward and try to insert it into the genital pore of the Mexican females," says Valero. "In some cases, we think they did insert it, because we saw the skiffia females jerking away." Sexual harassment of native species by an invasive species has been suggested before in a very different animal – the mink. "The story is intriguing but slightly speculative," cautions David Macdonald, director of the Wildlife Conservation Research Unit at Oxford University in the UK.

American mink, which escaped from fur farms and invaded the European and Russian countryside, are the main threat to the endangered European mink.

“POINTLESS” REPRODUCTION

Although evidence overwhelmingly suggests that the American mink brutalise the native species and have driven them to near-extinction through violent interactions, it is possible that male American minks may also attempt to reproduce with female European minks.

As with the guppies and skiffia, the females of the two species look similar. "There is tentative evidence that this mating has led to non-viable hybrid offspring," says Macdonald. If this is indeed happening, such "pointless" reproduction would reduce the number of European mink.

Valero and her colleagues now want to determine whether such interactions do leave female skiffia wounded and if they affect their future reproductive success.

"For me, the most interesting question is whether Mexican females respond differently to their own males after being harassed by guppies?" Valero says. "Do they then 'fear' males? We now know harassment between very different species exists," she says. "It is happening in lab and, because the species live in the same spots, it is definitely going on in nature too."

Journal reference: Biology Letters (DOI: 10.1098/rsbl.2007.0604)

ROLLERCOASTER OF FISHKEEPING/

MUSICAL FISHTANKS.                                    DIANA ANDREWS

Well, I can’t believe it’s been two years since I last put pen to paper, time does fly when a fish or two pass your way!!

It’s all been relatively quiet on the fish front in the Andrews household, well almost after the common sense of going down to only two tanks, which of course we still have, but, whilst on a shopping trip we saw a ‘Globe’ , and very soon space was made for this in the living room and very nice it looked too.  It made the fish and the plants look much bigger – not very easy to clean but nevertheless - minor detail!  Ray had acquired some Sailfin Mollies from Gerry’s and these looked quite superb in this new ‘Goldfish Bowl’. “I don’t know” said Ray one day “these don’t seem to be breeding at all” and he even said this to Gerry on one of our shopping trips.  Fatal mistake - one should learn never to make bold statements because not very long after on passing by the ‘Bowl’ there seemed to be quite a commotion.  As ‘mum’ was giving birth the males were having their breakfast!!  A rush for the nets and the two males were hoiked out leaving mum in peace.

  We had managed to save quite a few.   Well that was the start of things to come.  Another trip to Gerry’s to get a different colour (gathering a bit of momentum now) - somehow common sense seems to go out of the window when you see a nice fish.  Back home the Bowl seemed to be quite small – strange that - a total revamp of our three tanks – well no four actually,  I forgot to mention the other little new tank, the ‘hospital’ tank in the hall, (we must really stop going into these fish shops!)  which we brought just in case - well just in case of anything really.  But yes a total revamp was on the cards; well these babies and parents have got to have some room!! 

We had only four goldfish enjoying life in the 80 gallon tank in the hall, so they packed their bags and moved into the Bowl, bit of a come down, and the Sallfin’s moved into their tank.  Then of course the big tank looked quite empty, even though the Saillfin’s

were now breeding like rabbits!!  Never satisfied!!  Fortunately on another one of our shopping trips, yes again! we came across some black and white Sailfin’s (yes of course we bought them!) and they seem quite at home along with the orange and green ones.  Some of the babies are looking quite different!!

 The plants are growing quite amazing, something we have never had with the goldfish, but then they are quite messy things, and of course this gives plenty of hiding places for the little ones.  The goldfish seemed quite a home in the Bowl, but it was a bit small, so they packed their bags AGAIN!  (It’s a good job we don’t know what their thinking!) And moved to the 20 gallon tank in the living room – you know the one which housed the tropical fish, or ‘My’ tank as it was always known - Ray’s being the 80 gallon jobie in the hall.  Our house has always been quite different, some people have ‘his’ and ‘her’ towels, chairs, mugs, etc, in our house it was always ‘his’ and ‘her’ fish tanks.  So ‘My’ tropicals have now joined the Sailfins along with some lovely Clown Loaches which we brought to eat the snails and yes they have earned their keep.

 They are so lovely, they periodically lay on their side all piled on top of one another, (we have 5) or they lean against the rocks.  The very first time we saw this we thought they had all died!!   The goldfish are quite happy in their new surroundings and our conscience feels better!!  So the Bowl was now empty – washed and cleaned and put away in storage, along with the hospital tank – we had another tidy up in the hall!!   So strangely enough we have TWO fish tanks again - DEJAVU or what!!!!

         Green Sailfin Mollies.                                      Orange Sailfin Molly.

SEAHORSE PROTECTION                                   NEIL GARRICK – MAIDMENT

 This is an extract from an email sent by Neil to inform us of the really great news that our local Seahorses have been given protection:

“We had some fantastic news yesterday (28/2/2008), as a direct result of the British Survey run by the Seahorse Trust both British Seahorses have named protection under the Wildlife and Countryside Act (1981). Not only are the Seahorses protected but also the habitat they live in.

I would like to give a massive thanks to all those who have helped and supported the survey to make this possible.

This is the statement from Joan Ruddick, Minister for Biodiversity:

“The Water Vole together with the Angel Shark, Roman Snail, Spiny Seahorse and Short – Snouted Seahorse will gain protection against being killed, injured, or taken from the wild from 6^th.April 2008. They will join the list of wildlife species such as the Otter and Grass Snake that enjoy protection under the Wildlife and Countryside Act 1981.

                   Short-Snouted Seahorse                                       Spiny Seahorse

In addition, the possession or selling of the Water Vole, Short – Snouted Seahorse, Spiny Seahorse and Roman Snail will become an offence. It will also become an offence to damage or obstruct the Short – Snouted Seahorse and Spiny Seahorses’ place of shelter or disturb them in their place of shelter”.

THE SPINY SEAHORSE (Hippocampus guttulatus):

The Spiny Seahorse is a large Seahorse; it can reach up to eight inches from the top of its head to the tip of its tail, which appears very bony with distinct body ridges and a distinctive head and neck “mane” of appendages. These appendages give the Seahorse its name and are one of the main distinguishing features. It is often found with olive green colouration but can camouflage itself to its environment. This Seahorse can be found in beds of Eel Grass around our Devon and Cornwall coastline.

THE SHORT-SNOUTED SEAHORSE (Hippocampus hippocampus):

This is a stocky Seahorse up to six to seven inches. It is more barrel-chested than the Spiny Seahorse The snout gives it its distinctive name and is shorter and broader than the Spiny Seahorses snout. It is designed to feed on larger items of food on more rocky environments. They are found on our South Devon and Cornwall coastlines

THE ANGEL SHARK (Squatina squatina):

The Angel Shark in the UK is known as Monkfish and has been sold for human consumption since 1970’s and known as the “poor mans’ scampi”. It is found on continental shelves from close inshore to at least 150m depths. It lies buried in sand or mud with only its eyes protruding. It feeds mainly on bony fishes, but also Skates, Crustaceans and Molluscs. Its length is up to 1.83 meters and reproduction is ovoviviparous, with 9 to 20 “pups” per litter.

Water Vole (Arvicola terrestris)                 Roman Snail (Helix pomatia)