Fish Reproduction – an Amazing Array of Strategies and Styles

Hello, Frank Indiviglio here.  In terms of species diversity, fishes are the most successful of all vertebrates…with over 25,000 species identified so far, they outnumber mammals, reptiles, amphibians and birds combined.  Ranging in size from 2/5 of an inch to over 40 feet in length, one fish or another has colonized every aquatic habitat imaginable, from desert pools of 104 F in temperature to frigid Antarctic seas.  

In keeping with this remarkable diversity, fish reproductive methods are also extremely varied.  Today I’d like to convey some interesting facts concerning the breeding habits of both aquarium and non-pet trade species.

Placing the Young out of Harm’s Way

Mouthbrooding FrontosaAll American and European eels, whether inhabiting a bay in New Jersey or a pond in England, originated as eggs laid in the Sargasso Sea, off Bermuda.  Eels, salmon and many other fishes engage in massive breeding migrations, with millions of adults laying eggs simultaneously and then dying shortly thereafter. 

Most fishes lay eggs (up to 35 million per season in some cases), but a great many are live bearers that reproduce via internal fertilization.  Many merely scatter the eggs or fry and leave them to take their chances, while others take great precautions in preparing nests, guarding the eggs and caring for the young. 

Adult tilapia and many others protect their young by taking them into their capacious mouths at the slightest hint of danger, while male bullhead catfish accompany their offspring on feeding forays for several weeks (please note the photo of a brooding Cyphotilapia frontosa – youngsters can be seen within the parent’s mouth).  Perhaps most surprising of all, discus fish produce unique skin secretions that serve as food for their fry.

Switching Sexes and Sex Roles

Many fishes depart radically from what we’ve come to know as “typical” vertebrate reproduction.  Female seahorses, for example, deposit their eggs in the pouches of the males.  The males then act as “surrogate mothers” – regulating the salinity of the water in the pouch, brooding the eggs, and bringing forth the young. 

Wrasses, many species of which are kept by marine aquarists, begin life as females, with a number becoming males at a later point, a phenomenon known as protogyny. 

The ever-popular clownfishes utilize an equally unusual reproductive strategy, known as protandry.   All clownfishes fishes start out as males, and some later change their sex and wind up as females. 

Cloning (with a twist)

The Amazon Molly (Poecilia formosa) adds yet another variable to its reproductive strategy.  Named for the female-only Amazon Tribe of Greek Mythology (it ranges from southern Texas to northern Mexico, and is not found in the Amazon River), only females are known.  They must, however mate with a male to stimulate egg development – but there are no male Amazon Mollies. 

Female Amazon Mollies solve this dilemma by mating with males from one of several related species that share their habitat.  None of the “father’s” genetic material makes it into the young mollies however – these are all clones of their mother!

Well, we could go on for pages…I’ll add other interesting tidbits in the future.  Until then, please write in with your own odd facts and any questions you may have. 

Further Reading

To learn why inbreeding has not doomed the Amazon Molly to extinction, please see this article.

To read more about seahorse reproduction, please see my article The Care and Natural History of Native Seahorses.

Thanks, until next time,

Frank Indiviglio

Mouthbrood image referenced from wikipedia and originally posted by MidgleyDJ photo by Matthew Miller

Artist’s Exhibits Embody “All Washed Up”

Hey, it’s Eileen again! Last summer, I posted a blog on artificial reefs and their wide range of uses and designs, but an English artist is taking this concept to a whole new level!

Jason de Caires Taylor, an underwater naturalist and diving instructor with over 14 years experience underwater, has created magnificent underwater sculpture exhibits.  The exhibits are located in Grenada (Moilinere Bay) and the United Kingdom (Canterbury and Chepstow) with a sister exhibit on land in Crete, Greece. His exhibits highlight the underwater environment and its ability to change and adapt. Instead of scrubbing each bit of algae and growth from the artwork, it has become part of the exhibit.

As the underwater life reclaims each piece of Jason’s artwork, it helps illustrate his point on the resilience and adaptability of his exhibit. Most of his sculptures are of human figures, a truly haunting picture as the sealife starts to overtake them. His latest sculpture is incorporating a collection of glass bottles with messages submitted by the public and divided into categories like fear, hope, loss and belonging. Another project to be installed in Cancun incorporates propogated corals and over 400 individual sculptures.

Check out the gallery on the artist’s homepage and don’t forget these pictures the next time you are scrubbing the algae off your ornaments!

So, You’ve Got Questions About Reverse Osmosis Water?

Hi everyone, Justin here. Working on the sales floor, we get a lot of technical aquarium questions, many involving water quality.  Today, I’d like to talk a little about reverse osmosis and what RO units do.  RO, or Reverse Osmosis units are the best way to ensure that your water is perfectly clean. Reverse osmosis is a process in which dissolved solids are removed from water. The pressure from your tap forces the water through a semi permeable membrane that allows only water to pass through. The contaminants are then washed out in the waste water.

There are many factors that will determine the efficiency of your RO filter. Incoming water pressure should be around 60 psi. This is standard pressure coming from most hoses and sink faucets. If the pressure is too low, a booster pump may be necessary to increase the pressure into the RO unit. Water temperature is another important factor. Water that is too cold will cause a drop in pressure, while water that is too hot will damage the membrane. A suitable temperature range is 60-75 degrees F. Total dissolved solids, or TDS, is the measure of the amount of solids dissolved into your water. The higher the TDS in the tap, the quicker the membrane will wear out and need to be replaced. The age and quality of the membrane will also determine the effectiveness of the RO. A new membrane will pull out more TDS than an older membrane. A higher quality membrane will also be more efficient and last longer.

RO membranes will remove contaminants on an ionic level. This means that the membranes will remove single ions and particles as small as 0.001 microns. As a reference, the smallest known bacteria is approxiamately 0.200 microns. Below is list of the ions removed and an average percentage removed:

TYPICAL REJECTION CHARACTERISTICS
OF R.O. MEMBRANES

Elements and the Percent R.O. Membranes will remove

  Sodium

Sulfate

Calcium

Potassium

Nitrate

Iron

Zinc

Mercury

Selenium

Phosphate

Lead

Arsenic

Magnesium

Nickel

Fluoride

Manganese

Cadmium

Barium

Cyanide

Chloride

85 – 94%

96 – 98%

94 – 98%

85 – 95%

60 –75%

94 – 98%

95 – 98%

95 – 98%

94 – 96%

96 – 98%

95 – 98%

92 – 96%

94 – 98%

96 – 98%

85 – 92%

94 – 98%

95 – 98%

95 – 98%

84 – 92%

85 – 92%

% may vary based on membrane type water pressure, temperature & TDS

There are two different types of membranes commonly available, CTA and TFC. CTA stands for cellulose tri-acetate and is safe for use with chlorine-based water sources. CTA membranes should be used for City Water sources. TFC stands for thin film composite and is not safe for use with chlorine based water sources. TFC membranes must be used with well water, or chlorine free water sources only.

Inside the lines of each RO unit are flow restrictors to ensure proper pressure and flow over the membrane. These flow restrictors are small “dams” or nozzles that allow only a certain amount of water flow through the lines. The membranes coupled with these flow restrictors are made to handle the maximum flow of water through the restrictors. Placing a membrane rated too low into the unit will ruin the membrane, while placing a membrane rated too high will not increase production of water.

There are many different styles of RO filters available. 2 Stage and 3 stage filters are the most commonly available, but other higher stage filters are also available. On all two stage RO filters, there is the membrane, a micron cartridge, and a carbon block. The micron cartridge pulls out tiny particles that may be in the water. The carbon block will pull out any organic contaminents before entering the membrane. The membrane is the last stage in all 2 stage filters. In 3 stage filters, the last stage is a deionization cartridge. The deionization cartridge or DI removes any ions that may have passed through the membrane. The 3 stage RO/DI filters are the most efficient and will guarantee clean water.

I hope this article helps you to understand what RO units do and how they benefit your aquarium and the fish you keep.  Feel free to comment or ask any questions you may have!

Thanks,

Justin

Heteropsammia cochlea – Fascinating Walking Dendros Worming their way into Reef Aquariums

Hey all, Cory here.  Ever hear of a coral that walks where it needs to be?  If not, you’re in for a treat as I introduce you to a new arrival, the Walking Dendro.

We just received our first Walking Dendro, Heteropsammia cochlea, last week. At first glance, you may think this was a solitary coral that you would find on the backside of your new Clove Polyp or Mushroom rock. However, upon further inspection, this small coral has a very intricate story.

Walking Dendro Coral is now being imported from Australia for the first time for the aquarium trade. Previously, these corals were imported for research and not so much sale. It may look like a Balanophyllia, but the Walking Dendro is far from a solitary coral.  A symbiotic worm gives it mobility!

Walking DendroThe story begins with a single coral larvae finding a small snail shell on which to attach and begin it’s life. From this point the coral can begin to lay down its structure, quickly overgrowing the shell. For one reason or another a Sipunculid Worm moves into the shell, only to become engulfed and trapped inside the coral. This symbiotic relationship allows for constant movement for the coral and safety for the worm. The coral will have a small hole on the bottom allowing for movement and the uptake of sediment by the worm, preferably a fine sand. The worm is a deposit feeder, taking up sand and consuming nutritious organics found in or on the sand. The coral itself is photosynthetic, but with the presence of tentacles during the day, I would suspect they are also planktonic feeders.

Since there is very little known about this coral, it’s difficulty and hardiness are hard to specify. The coral itself should be easily kept, it is the Sipunculid worm or peanut worm that may be difficult to satisfy.

It is always exciting to see a new coral introduced into the hobby, because it is not only another organism to add to the inventory list, but a learning experience to even the most knowledgeable. As soon as there is any new information regarding the Walking Dendro to report, I will be sure to bring it to you.  Stop in and check them out!

Thanks, Until next time,

Cory

January Teaser – The Upcoming 2010 Winter Frag Swap Event

That’s right! The NCPARS/That Fish Place Winter Frag Event will be back again in just a few short weeks! On Saturday January 30th from 11 pm-5 pm, we’ll be hosting NCPARS (North Central PA Aquarium Reef Society) members and  coral fraggers and collectors from near and far for the biggest fragging event of the season. Industry experts and vendors will be here to help you with reefing and fragging needs, there will be fragging demos, and LOTS of frags, fish, inverts and other goods. Save the date for this fun and frag-filled event!

Last year’s event was a big success and hundreds of beautiful coral frags found new homes. For more details and to register visit fragswapper.com. and watch for more updates at ThatFishPlace.com closer to the big day!  Admission will be 5.00 for members and 10.oo for non-members, and there will be bargins galore. 

See you then!