That Fish Blog – Aquarium Advice and Information

Hello, Frank Indiviglio here.

Please see Parts I and II of this article for general information and for details concerning the care of elephant nosed and butterfly fishes.

Dwarf Clawed or African Dwarf Underwater Frog, Hymenochirus boettgeri, H. curtipes

This tiny (males to 1 inch, females to 1.4 inches) aquatic frog is a real pleasure to keep.  It is perpetually on the prowl, sticking its pointed little head into every nook and cranny in its ceaseless search for food.  A group so engaged is really quite comical to behold…they look like nothing so much as squadron of tiny, flattened divers!

Habitat and Habits

Dwarf clawed frogs move slowly about the aquarium bottom and among the plants, and save “free swimming” for trips to the surface for air.  In deep aquariums, they do best when provided with “ladders” to the surface in the form of (preferably live) plants.  They are at their best in heavily planted aquariums, and will utilize every square inch available to them. 

Small size and bold demeanors render these frogs ideal observation subjects. It is quite easy to provide them with a habitat in which they will reveal to you nearly all of their natural behaviors, and captive reproduction is not uncommon.  Dwarf clawed frogs are not favored aquarium animals in the USA, due largely to the fact that they are usually kept improperly.  Typically housed in bare tanks with active fishes that out-compete them for food, they usually expire in short order. 

Feeding Dwarf Clawed Frogs

In addition to dense cover, dwarf clawed frogs need a varied diet of small, live invertebrates.  Blackworms can account for up to 75% of their food intake, supplemented whenever possible with live brine shrimp (brine shrimp alone are not an appropriate diet), whiteworms, bloodworms, mosquito larvae and similarly-sized aquatic organisms.  Newborn guppies may be taken by particularly large individuals.  I’ve had my best breeding results when I provided my frogs with occasional meals of pond-seined fairy shrimp and other tiny invertebrates.

I have not had much success in inducing dwarf clawed frogs to accept non-living food items, but others have reported good results with some individuals.  I suggest that you feed them as described above, but experiment with Reptomin Select-A-Food  (freeze dried and pelleted components), freeze-dried fish foods  (mysis shrimp, daphnia, bloodworms) and frozen mosquito larvae.

As dwarf clawed frogs feed largely by day and elephant nosed fishes by night, competition for live blackworms is rarely a problem.

A Unique Hunting Strategy

Dwarf clawed frogs use a suction-based feeding technique, unique among amphibians, to capture their prey.  The tiny hunters lunge forward while extending the front limbs and opening the mouth, after which the body is recoiled.  Like other members of the family Pipidae (African clawed frogs, Surinam toads), dwarf clawed frogs are tongue-less.

Hybrids and Feral Frogs

Only Hymenochirus boettgeri and, to lesser extend, H. curtipes, appear in the trade; there is some evidence of hybridization between the two.  H. boettgeri has been introduced to Florida and is apparently well established.

An Important Distinction

It is important that you are able to distinguish this frog from young African clawed frogs (Xenopus laevis).  The two are frequently housed together in pet stores….Xenopus grows quite large and will consume smaller frogs, fishes and shrimp.

In dwarf clawed frogs, the appendages of all 4 limbs (fingers and toes) are webbed; Xenopus possesses webbed feet only.  Dwarf frogs are also more flattened in body form, and their heads are very narrow, nearly “pointed”.

Giant African Fan Shrimp, Atya gabonensis

This stoutly-built West African native is bound to become more popular as time goes on.  Built more along the lines of a crayfish than a shrimp, yet completely benign toward tank-mates, it feeds by sweeping food into its mouth with feathery appendages.  Fan shrimp are quite social in nature, with groups often sharing the same shelter even when others are available. 

The Importance of Shelter

I have found African fan shrimp to be compatible with the other animals mentioned in this article, provided that they have access to secure shelters.  They seem to be very much “home oriented”, and become quite stressed when their retreats are disturbed in any way. 

Be sure to supply your shrimp with caves and other such hideaways that will not be disturbed by foraging elephant- nosed fishes (the other species pose no concerns), and do not move the shelters once they have been occupied.  Small rock dens  or Mopani wood shelters  are ideal.

Please see my article on the Natural History and Care of African Fan Shrimp  for husbandry details.

I was recently told of an unusually large (possibly 8 inch) fan shrimp that was residing in a local pet shop.  I went to see the animal, only to find that it had expired and had been discarded.  Please write in if you have observed fan shrimp larger than 5 inches or so – we have a great deal to learn about this animal…perhaps there is more than 1 species in the trade.

Further Reading

You can read more about the dwarf clawed frog and its relatives at http://research.amnh.org/herpetology/amphibia/names.php?taxon=&family=&subfamily=&genus=hymenochirus&commname=&authority=&year=&geo=0&dist=&comment=.

 

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

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

Hello, Frank Indiviglio here.

The African fan shrimp is not well established in the aquarium trade, but interest is growing.  I have maintained a group for approximately 2 years, and have found them to be fascinating, if a bit challenging in some respects.  Their mode of feeding is particularly interesting, but requires a bit of attention as to “presentation”…I’ll write more about that in Part II of this article.

NATURAL HISTORY

This shrimp inhabits rocky streams along the west coast of Africa, from Senegal to Gabon.  It is also recorded from the east coast of South America; however, the genus is not well studied and these populations may represent a different species.  Their natural history is not well-documented.

African fan shrimp are heavily-built and reach 4 inches in length.  The first 2 appendages are equipped with feathery bristles which are swept back and forth when the animal is feeding.  Most in the trade are tan to dark brown in color, but blue, yellow, pink and red specimens show up on occasion.

CAPTIVE HUSBANDRY

Captive Habitat

The Aquarium

A well-filtered 10 gallon aquarium will comfortably house 4-5 shrimp.  They seem quite social; I have keep 12 in a 55 gallon aquarium.  The tank should be well covered, in case they decide to explore by climbing filter tubes or heaters.

Heat and Light

I keep my fan shrimp at 76 F; their temperature range is reported to be 74-88F.

African fan shrimp only leave favored retreats at night, and then infrequently.

A Night Glo bulb  or similar bulb will allow you to view their nocturnal activities.

Substrate

A rock or gravel substrate is preferable, as such is what would be found in their native habitat.  However, people keeping these shrimp on sand report no problems.  They do not negotiate bare-bottomed tanks well, and seemed stressed by the effort.

Physical Environment – Habitat Type and Terrarium Decorations

African fan shrimp are very shy and retiring, and require suitable shelters if they are to thrive.  Mine seem quite specific in their choice of a retreat – once they settle in, they remain within the same cave or shelter, even if others are available.  I have observed several shrimp to occupy the same small caves for 18 months.

They will utilize rock caves or artificial structures and ornaments.  Despite their need for privacy, the shrimp seem unconcerned about being on view through glass…caves positioned near the aquarium’s glass will allow easy observations.  They prefer a “tight fit” over a spacious cave, and many will remain within one shelter, usually in physical contact with one another, if able.  I’m not sure if they prefer to live in groups (field studies are in short supply) or not, but they certainly do well when provided with a cave that allows them to congregate.

Water

Hailing as they do from fast-flowing streams, fan shrimp likely have high oxygen requirements, so be sure that your tank is adequately aerated.

They should be maintained at a pH of 6.5-7.4.  I use soft water, but this is not based on field research (in fact, water in rocky streams tends to be hard).

Like many invertebrates, fan shrimp are extremely sensitive to ammonia, and to copper and other chemicals that are found in fish medications.

I’ll finish up with feeding and  pass along a few observations next week.

We have much to learn about these and other fresh water shrimp… please write in with your questions and observations. Thanks, Frank Indiviglio.

A video of an African fan shrimp in the process of feeding is below: