That Fish Blog – Aquarium Advice and Information

Hello, Frank Indiviglio here.

Please see Part I of this article for information concerning typical brackish water plants and algae.

A number of well-known freshwater aquarium plants adjust quite nicely to brackish water.  Given the great variety of species that are available, I’m sure many others will be found.

Experimenting With Freshwater Plants

If you are of a mind to experiment, first research various natural habitats, keeping an eye out for plants that thrive along coastlines, estuaries and in other such situations….these might be exposed to salt water during floods or at high tide.  In general, freshwater plants with waxy leaf and stem coverings make the best prospects with which to begin.

Bear in mind that the change from fresh to brackish water is an extreme one, and can easily shock your plants.  Treat them as you would a new, delicate fish and increase their exposure to brackish water gradually.  For untested species, you might consider dripping brackish water into the plant’s tank via a section of airline tubing during the acclimatization period.

Anachris (Egeria) densa

Much favored by freshwater aquarists and a standby for grammar school science experiments, Anachris is very hardy and highly recommended for use in brackish tanks.  Most agree that it is the most likely of all freshwater plants to thrive in this foreign environment.

Anachris grows well as a rooted or floating plant and, in strong light, can add an inch or more a day to its length.  Cuttings taken anywhere along the stem will grow into new plants.

Temple Plant, Hygrophila corymbosa

This most attractive of aquarium plants does very well in brackish water, but is considered a delicacy by snails, hermit crabs and many fishes.  It and related species, which are native to South and Southeast Asia, can be propagated from cuttings and grow best under bright lights.

Cabomba aquatica

Another popular freshwater plant, this South American native has delicate leaves which cannot withstand the attentions of herbivorous fishes and invertebrates.  However, when housed with halfbeaks, mudskippers and others that will not molest it, Cabomba makes a fine addition to the brackish aquarium.

Aquatic Grasses – Sagittaria and Vallisneria

Sagittaria, relatively impervious to salt water damage and unpalatable to most organisms, is one of the best freshwater plants to use in brackish systems.  The widely-available grass Vallisneria does very well also, even under subdued lighting, but is considered a tasty food by many aquatic animals.

Hornwort, Ceratophyllum demersum

Reaching 10 feet or more in length in the wild and equally at home in cold and warm water, this hardy survivor is an excellent candidate for brackish water tanks.  It can get by in dimly-lit aquariums, but in such situations its foliage will pale considerably.

Water Sprite, Ceratopteris thalicroide

Even in such an unnatural environment as brackish water, this plant will grow quite vigorously if kept warm and under bright lights.  It can be maintained either floating or rooted, and in different situations will develop rounded, bulky or fern-like leaves.  Water sprite’s prodigious rate of growth often compensates for the attentions of plant-eaters.

Chain Swordplant, Echinodorus tenellus

This attractive plant spreads rapidly via runners (hence the “chain” portion of its name) and is fully grown at 4 inches in height.  As is true for its larger relatives, the chain sword requires warm water and a well-lit environment.

Further Reading

Anachris (Egeria) densa is widely introduced in the USA and elsewhere.  The University of California has posted an interesting account of its natural and unnatural history at http://ucce.ucdavis.edu/datastore/detailreport.cfm?surveynumber=182&usernumber=43.

Please write in with your questions or to relate your own experiments with aquatic plants.  Thanks, until next time, Frank Indiviglio.

Hello, Frank Indiviglio here.

The culture of live algae and plants in brackish aquariums has not been given much attention, and few plants native to estuaries and similar environments are commercially available.  However, as with fresh water tanks, live plants add a whole new dimension to aquarium-keeping, and are extremely interesting in their own right.

In brackish exhibits at the Bronx Zoo and in my own tanks, I have experimented with several varieties of algae and plants.  In addition to mangroves, Java ferns and other such estuarine-adapted species, a surprising number of plants and algae that are typically thought of as either “marine” or “fresh water” can be acclimated to brackish environments.  Following are a few of my favorites.

Acclimatization

Plants and algae should be introduced carefully to a brackish water aquarium…treat them as you would a fish or invertebrate.  Particularly as concerns fresh-water plants, sudden changes in pH can wreck havoc with osmotic pressure, causing cell rupture and the death of the specimen.

Marine Algae

Marine algae are commonly referred to as “seaweeds”, but they are in actuality not true plants.  Single or multi-celled, algae lack roots, stems and leaves, but have evolved equivalent structures. For example, holdfasts act as roots in anchoring them to the substrate, but do not absorb nutrients…that role is taken on by the leaf-like portions of the organism.

Caulerpa prolifera

This is the most commonly-available marine algae.  It ranges from Florida and the Caribbean southward, and is commercially cultivated.  Caulerpa spreads via rhizomes, or runners, and, although a true marine algae, it adjusts well to brackish environments.

Like all algae, Caulerpa may leak fluids when pruned, so be sure to clip only a tiny amount at a time if trimming is necessary.  Related species, with rounded, pointed or fern-like shapes, are sometimes seen in the trade.

Other Types of Marine Algae

A number of other types of marine algae are sometimes available.  While not as well-suited to a brackish water existence as Caulerpa, several will adjust if care is taken in the acclimatization process.

I and colleagues have had varying degrees of success with sea cactus (Udotea flabellum), Codiacea spp., mermaid’s cup (Acetabularia spp.), mermaid’s shaving brush (Penicillus capitatus) and several types of red algae.

Brackish Water Plants

Java Fern, Microsorium pteropus

To my knowledge, the Java fern is the only true brackish water aquatic plant that is regularly available to aquarists.  In well-lit tanks it will proliferate rapidly.  A number of fishes favor Java fern leaves as food, but its rapid growth rate can accommodate this in many cases.

Red Mangrove Seedlings, Rhizophora mangle

Mangrove seedlings, or propagules, are semi-aquatic, with the roots usually submerged and the plant itself growing above water.  The red mangrove is often sold in the trade and is commercially propagated in Florida, where it also occurs naturally.  Red mangroves are extremely wide-ranging, being found along coastlines in many of the world’s tropical and subtropical regions.  At home in estuaries, salt marshes and along river mouths, they are adapted to fluctuating salinity levels, and fare well in brackish water aquariums.

Mangroves can be planted in mud or wedged into limestone, and, because of their semi-terrestrial nature, are best kept in aquariums housing mudskippers, fiddler crabs and other creatures that utilize both land and water areas.  They excrete salt on the surface of their leaves…this should be washed away with fresh water every few days.

Mangroves often grow slowly in the aquarium, and stay at a manageable size for some time.  There are a few techniques for dealing with tall plants…please write in if you would like further information.

Eelgrass, Zostera marina

Eelgrass is one of the only true plants to live an aquatic existence in marine environments.  It is not commonly kept in aquariums.  I have had mixed success with it, but have observed healthy stands in commercial aquariums (if you are interested in this plant, please write in and I’ll make some inquiries to public aquarium contacts).

Eelgrass populations have plummeted in the northeastern USA and elsewhere, and I encourage those with an interest to work with this plant (please note that collection is prohibited in California and elsewhere).  An incredible assortment of unique fishes and invertebrates, such as pipefishes, dwarf seahorses and eelgrass-shaped amphipods, are always found in association with eelgrass beds.

I commonly observe eelgrass in estuaries, lagoons and other brackish habitats, and it thrives in true marine water as well.

Next time I’ll discuss some of the many fresh water plants that can be acclimated to brackish conditions.  Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Brackish environments are home to many fascinating fishes and invertebrates that do well in aquariums.  Please see my article on Mudskippers  for a look at one of the most unusual.

Hello, Frank Indiviglio here.

Two articles addressing fresh water and marine fish conservation issues were published this week:

Oriental Weatherfishes in Spain

According to an article in Biological Invasions, the Oriental Weatherfish (native to eastern Russia, south and Southeast Asia) is now well established throughout Spain’s Ebro River delta, and has a foothold in the Onyar River as well. This is of particular concern because over 80% of the Iberian Peninsula’s freshwater fishes are already considered to be threatened, with introduced species outnumbering natives in most rivers.

Last year, studies of the eel fishery in the Ebro River revealed that 8.2 tons of non-target fish, representing 17 species, are captured along with each ton of eels (elvers) harvested.  Approximately 40% of these fish perish before they can be released.

Fishes of the Coral Triangle

Reef fishes are becoming increasingly popular on restaurant menus throughout Southeast Asia and mainland China.  Particularly hard hit are species native to the waters bordered by Malaysia, Indonesia, Papua New Guinea, the Philippines, East Timor and the Solomon Islands.  Known as the “Coral Triangle”, this region is home to 75% of all known species of coral.

According to a recent Conservation Biology article, spawning aggregations of local species have declined by 79% in recent years, largely due to over-fishing.  Groupers, 26 species of which are endangered, have suffered the most.  Conservation efforts are complicated by the large number of countries having interests in these waters.

Thanks, until next time, Frank Indiviglio.

For further information on the natural history and captive care of weatherfishes, please see:

http://blogs.thatpetplace.com/thatfishblog/2008/05/22/fish-for-the-cold-water-aquarium-%e2%80%93-the-oriental-weatherfish-misgurnus-anguillicaudatus-the-european-weatherfish-misgurnus-fossilis/

Classification

More than 200 species of moray eels, all classified within the Family Muraenidae, have been described.  Like the familiar American eel, morays are considered to be true eels of the Order Anguilliformes.  The Superorder to which all eels belong, Elapomorpha, contains over 800 species, including the decidedly “un-eel like” tarpon.

Natural History

Although usually associated with tropical and subtropical habitats, a number occur in temperate seas, and several enter brackish and fresh water on occasion.  Ranging in size from the red-faced eel (Monopenchelys acuta), which reaches only 8 inches in length, to the 12.5 foot long giant green moray (Strophidon sathete), all share a similar body pattern and habits.  The latterly flattened body allows them access to the narrow caves and crevices that form their home base.  Many spend their entire lives within close proximity to a favored shelter, leaving only to mate and foraging nearby.

Some Interesting Facts

Morays can reach quite high densities in suitable habitats, accounting for nearly 50% of the carnivore biomass on some reefs off Hawaii.  Although nowhere considered a delicacy, moray eels are eaten on occasion, and instances of fatal poisoning (ciguatera) have been reported in the Philippines.  A number have unusual life histories…the leaf-nosed moray (Rhinomuraena quaesita) begins life as a dark blue-and-yellow colored male and later transforms into a black-and-yellow female.

Diet and Feeding

Moray eels are carnivorous, and in captivity will readily accept frozen silversides , sand eels , clams  and other fish, crustaceans and mollusks.  Local seafood markets are wonderful shopping grounds for the moray owner – be sure to try mussels, conch and various marine fishes.

Well-fed eels will coexist with smaller fish, but there is always the possibility of predation.  On the other hand, morays are not quick feeders, and indeed can be rather shy about this, so one must take care that they are getting enough food if they are housed with large, aggressive fishes.

Cautions

Moray eels are, like all their relatives, master escape artists.  If this occurs, be sure to move the animal back and forth in the aquarium once it is replaced, so that water is forced through the gills, and treat it with Stress Coat Marine to help replace the skin’s slime coat.

Even small morays are equipped with needle-sharp teeth, and they are not shy about using them in defense or if they mistake your finger for a tasty food item.  The resulting wound almost always becomes infected, and large animals can cause permanent damage.  These are definitely not fish for homes with children.

Longevity

Well cared for specimens can reach impressive ages in captivity.  A huge green moray I worked with at the Staten Island Zoo is still going strong at age 30+.

Snowflake Moray, Echidna nebulosa

Brilliantly patterned in black and white, this Indo-Pacific native averages 24 (rarely to 40) inches in length and makes an ideal first choice for one new to keeping moray eels.  Many individuals become quite tame, reaching out from their lairs to accept food offered on feeding tongs.

They are, like other members of their family, slow feeders, and so are best individually-fed if kept in a community aquarium.  Snowflakes readily accept all manner of frozen or fresh marine foods such as shrimp, clams and fish.  Like all morays, they will not thrive unless provided with a secure retreat.

Other Commonly-Available Moray Eels

The girdled moray (Echidna polyzona) hails from the Red Sea and Indo-Pacific and its small size (to 35 inches) suits it well as an aquarium subject.  It has a relatively small head ….food item size should be adjusted accordingly.

The attractively patterned reticulated or leopard moray (Gymnothorax tesselatus) also appears in the pet trade.  Pale reticulations on a dark background lend it a spectacular appearance, but it reaches 5 feet in length and is therefore suited only to large, very well-secured tanks.

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

You can learn more about moray eels at:

http://www.fishbase.com/Summary/FamilySummary.cfm?ID=56&CFID=17425107&CFTOKEN=61585937

Hello, Frank Indiviglio here. Please see Part I of this article for further information.

Feeding

The fan shrimp’s unique mode of feeding is very interesting to observe.  The first 2 appendages are lined with plume-like bristles which are waved about when food is detected.  Tiny organisms, organic detritus and algae are trapped in these and transferred to the mouth.  Fan shrimp will also pick food particles from the substrate, in more “typical shrimp” fashion, and I have several times observed them feeding on dead fish (at night).

If you keep fan shrimp with fish, it is important to introduce food at night, just before you turn out the lights…the shrimp will rarely get enough to eat otherwise.  I keep a few yo-yo loaches, Kuhli loaches and armored cats with mine, but beware of adding too many nocturnally-feeding fish.

Unlike many shrimps with specialized feeding adaptations, these accept nearly any pelleted or freeze dried food.  One of the few published reports on their feeding habits in the wild (please see below) established that fan shrimp are omnivorous, with algae forming a major part of the diet.  I therefore provide my shrimp with both plant and animal foods.  I use algae  and shrimp tablets as a basis of the diet, alternated with flake and freeze dried foods.  Liquid invertebrate food  may also be squirted into their hiding places.

African fan shrimp begin waving their feeding appendages about as soon as food is sensed.  I usually drop algae tabs or other foods right near them, after which they will move over it and begin waving away.  If you look closely, you’ll be able to see fine particles of food lodge in the brushes as the tablet dissolves.

My fan shrimp do not gravitate towards the filter outflow in order to trap food, as do the Singapore wood shrimp (Atyopsis moluccensis) which share their tank.  They will, however, filter fine food particles from whatever water currents pass by their lairs.  Some suggest keeping these shrimp in well-established tanks that house high populations of diatoms and other micro-organisms.  Certainly this is a good idea, but as we know little of their actual food intake needs, I would suggest that shrimp in these situations be fed as described above as well.

Social Grouping/Compatible Species

African fan shrimp do exceedingly well in same-species groups; I have also kept them with Singapore wood shrimp, Atyopsis moluccensis, Japanese marsh shrimp, Caridina japonica and cherry shrimp, Neocardina denticulate.  Small, peaceful community fish such as guppies, zebra danios, cherry barbs and so on are also fine, but please see the feeding cautions above.

Alternatively, you can house fan shrimp with fish that do not compete for food, i.e. live food specialists such as elephant-nosed morymids and butterfly fish (both of which are also native to West Africa, although not to the same habitat-types).

Small and large cichlids, carnivorous catfish and crayfish will attack fan shrimp.

Captive Longevity

Unpublished reports set captive longevity at just over 5 years.

Breeding

Anecdotal reports claim breeding success in heavily-planted outdoor ponds.  The young are said to be planktonic for a period of 2-3 weeks after hatching, which would certainly complicate matters in an aquarium.  I plan to look into this further and report back.

Miscellaneous

Fan shrimp are, as mentioned, very much oriented to a specific home cave, being more like crayfish than shrimp in this regard.  I imagine (but this has not been established) that such holds true in the wild as well.  I have observed them to become quite stressed if routed from their retreats.  In most cases, they wander about, often for days, before returning to the cave.

Be extremely careful when working around them, and avoid moving or re-arranging their caves.  I usually forego cleaning the glass directly in front of their caves, unless I happen to catch the shrimp “away from home” on rare foraging forays.  In those cases I’m always careful to return the rocks to their original position – a slight change in their shelter’s height or depth has seemingly caused my shrimp to seek “new accommodations”.

We have a great deal to learn about this and other freshwater invertebrates… please write in with your questions and comments. Thanks, Frank Indiviglio.

Very little has been published about this species in its natural habitat.  An interesting article concerning field research with fan shrimp in Nigeria is posted at:

http://www.wajae.org/papers/paper_vol13/Food_and_Feeding_Habits_of_Atya_gabonensis_from_Lower_River_Benue_in_Northern_Nigeria_full.pdf