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Contains articles featuring information, advice or answering questions regarding aquarium fish and other livestock.

Live Foods for Fishes and Invertebrates – Daphnia, Copepods and Seed Shrimps

Daphnia magnaHello, Frank Indiviglio here. There was a time when all serious aquarists maintained live cultures of Daphnia. This practice has fallen out of favor today, with live foods being replaced by prepared diets. However, many tiny aquatic Crustaceans are easy (and interesting!) to maintain, and represent one of the most nutritious of all food sources for aquatic animals.

The animals highlighted here are especially valuable for fry and small or filter-feeding invertebrates, and are essential to the survival of tiny live food specialists such as seahorses and pipefishes. They can be used for freshwater or marine animals. Be aware, however, that freshwater species will expire rapidly in salt water, and vice-versa.

Daphnia

These tiny Crustaceans may easily be collected via plankton net (available at biological supply houses) from nearly any body of fresh water. Alternatively, a culture may set up by adding pond water and grass or hay to a tank placed in a sunny location (or use a full spectrum bulb).

Eggs or immature Daphnia magna, a very common species, will likely be present and, at 75-80 F, will mature within a week. This species reaches 0.25 inches in length (a Daphnia giant!) and is sometimes available commercially. Females produce 100 or more eggs every few days (with or without males), and so a healthy colony will easily meet the needs of most aquarists.

Daphnia fare best in tanks supporting a healthy growth of algae. While filtration is not essential, I’ve found a sponge filter
to be very beneficial (use a small air pump – strong currents should be avoided).

Decaying plant matter provides sufficient food, but growth and reproduction will be hastened if you supplement the culture with Artemia food , ground Spirulina discs and liquid invertebrate foods.

Copepods

Copepod kilsSmaller even than most Daphnia, Copepods are an excellent food source for the tiniest of fish fry, shrimps and filter-feeding invertebrates. I’ve used them for dwarf seahorses and newborn four-spine sticklebacks with great results.

Occurring in fresh and marine waters worldwide, over 5,000 species of these crustaceans have been described to date (Copepod taxonomists must be quite amazing people!). Cyclops fuscus, which reaches 0.124 inches in length, is the species most commonly encountered in the USA.

Copepods may be collected and raised as described for Daphnia.

Seed Shrimp or Ostracods

These aptly-named Crustaceans (Class Ostracoda) do indeed resemble tiny shrimps encased within a seed. The 13,000+ described species thrive in a nearly every aquatic habitat known, from the deepest oceans to the few drops of rainwater that collects in bromeliads growing in rainforest canopies. They are truly amazing in their range of forms and adaptations.

Seed shrimps “bounce” along the substrate, a habit that renders them an ideal food for bottom-dwelling aquarium pets. Although rarely cultured for food, I have found them to be quite hardy, and well worth the small effort involved in keeping them. Their exoskeleton is an excellent source of calcium.

Seed shrimp care is as described for Daphnia.

Useful Products

A number of highly nutritious crustacean-based foods are available to supplement live-food diets. The following are well-worth trying:

Further Reading

Despite their small size, seed shrimps are incredibly complicated creatures, and quite interesting in their own right. Read more about their structure and behavior at http://w3.gre.ac.uk/schools/nri/earth/ostracod/introduction.htm.

Please write in with your questions and comments. Thanks, until next time, Frank Indiviglio.

Copepod image referenced from Wikipedia and originally posted by Uwe Kils

Assassin Snails – Killer Snails for Your Aquarium

In my first blog, I talked about why the Zebra Loach (Botia striata) is well suited for smaller aquariums, and why it was certainly a more sensible choice for snail control than its larger cousin, the Clown Loach. The Zebra Loach is one of the most under rated of the snail eating Botia, in my opinion. But what if you have a planted aquarium and you’re keeping small shrimp? Zebra Loaches may very well eat them! Or what if you have a small tank, but don’t have room to house 4 or 5 of these fish? Well, I think there may be something that is just as effective, does not appear to want to eat the little shrimp, and won’t take up a lot of room. A somewhat new introduction into the hobby called the Assassin Snail.

The Assassin Snail (Clea helena or Clea Anentome helena) comes from lakes and ponds in Southeast Asia, where it feeds on decaying protein, worms, and other snails. That’s right, a snail that eats other snails. Voracious little predators, the Assassin Snail has an attractive yellow shell with a spiraling brown stripe wrapped around it. While they do have an appetite for snails, predation does not occur within their own species. This allows several individuals can be kept in a single small aquarium. At an adult length of just under an inch, a 10 gallon aquarium could easily house a dozen of these snails. They are pretty durable and can take a wide range of water chemistry, as long as it does not fluctuate greatly. While preferring a pH of 7.0 or 7.2, they can tolerate a range from slightly above 6 to about 8.2. Water hardness, can also be somewhat flexible. Reports of keeping them in water with GH values of 5 and a dKH of 1 seem to be pretty standard. Fine gravel or sand is always preferred, but not a necessity. If you do have fine substrate, these little guys will burrow and crawl through the substrate in search of food.

Assassin Snails are known to be extremely active. The idea that snails are slow and plodding is definitely challenged by this gastropod. Assassin snails will scale plants, glass, large stones, and wood with surprising speed when hunting for food. I have even seen them suspended upside down on the surface of very still water! Being able to move quickly gives this snail an advantage over slower moving prey items, such as the troublesome pond snail, Physa sp. In large numbers, Physa sp. pond snails can damage soft plant tissue and can present a real problem if you are trying to keep a well-groomed planted aquarium. A handful of Assassin Snails will eventually clear the aquarium of unwanted snails. After the problem snails are eaten, Assassin Snails will take up a somewhat more laid back role by eating left-over fish foods and decaying protein. While some reports of shrimp predation have occurred, it is a pretty rare occurrence.

Watching a group of these curious little snails cruising around your aquarium is really fascinating. I have never really gotten absorbed into the snail world, but seeing the Assassin Snail hunt and forage for food has definitely piqued my interest! From my personal observations, I have to say that these snails are definitely more than capable of ridding an aquarium of unwanted snails. They may be the predator you’ve been looking for.

Thanks, until next time,

Craig

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

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!