Malaysian Horned Frogs

Many examples of crypsis, the ability to avoid observation, are within the various taxa of the order Anura, but perhaps none are more spectacular than that of the Malaysian horned frog (Megophrys nasuta).

Several anatomical characteristics make Malaysian horned frogs look similar to large leaves. The body is dorsoventrally flattened, and the head is adorned with three fleshy projections. One protrudes from the rostrum, and one is over each eye. Two sets of dorsolateral folds running from the shoulder to the groin and a variable number of dorsum tubercles further breaks up the form. Dorsal coloration is typically a shade of either red or brown, and often darker reticulations similar to the veinlike pattern of a leaf are present. Although some animals have a deep-orange or red throat, it is usually dark brown with lighter shades of brown, gray or white, giving the appearance of a shadow. The belly is whitish or light gray.

Malaysian horned frogs show a high degree of sexual dimorphism. Females grow to approximately 71/3; inches long, and males attain a maximum length of a little more than 4 inches.

Challenging Charges

Malaysian horned frogs are generally rewarding captives, though maintaining the species long term and achieving captive reproduction can prove challenging. As with all reptiles and amphibians, purchasing a healthy individual is key.

The Malaysian horned frog is rarely bred in captivity, and most frogs currently available in the hobby are wild-caught. Reptile exporters in Malaysia often pack large numbers of frogs in the same container, which can predispose these animals to stress and infectious conditions. When the frogs arrive in the United States, they are often placed in overcrowded holding containers, compounding the stress and further weakening the amphibians’ immune systems.

Seek dealers mindful of overcrowding. If you’re dealing with someone through the Internet or over the phone, ask how the Malaysian horned frogs are housed at the facility. If you can observe the frogs in person, look for frogs housed individually in reasonably sized containers. On examination, look for eye clarity, and try to find active animals that do not appear emaciated or weak. After the purchase, try to get the animal set up as soon as possible, and keep the number of additional animals in the same enclosure to a minimum.

Keeping It Simple

There are a number of ways to house the Malaysian horned frog. During the acclimation period, select a simple setup that is easily cleaned. I prefer 66-quart Sterilite storage containers with opaque or solid sides. These help minimize stress in new individuals and help prevent rubbing against the sides, which can damage the amphibians’ fleshy “horns.”

One of my female Malaysian horned frogs developed abrasions over the horns. They became infected, and this delicate tissue was almost completely gone by the time the infection was under control. Using opaque-sided containers has eliminated these issues in my experience.

I have used moist paper towels as a substrate for years with no adverse effects. I also provide a shallow water bowl approximately 8 inches in diameter and 1 inch deep, so the Malaysian horned frogs can thoroughly soak in the evening. An alternative approach is to use a 2- to 3-inch layer of foam rubber on half of the enclosure and fill the other half with water to a level midway up the foam.

Lighting is an important concern for the care of Malaysian horned frogs. Appropriate light sources include UVB-emitting fluorescent tubes or compact fluorescents. Providing a source of UVB light allows many herps to naturally produce Vitamin D3, but generally this is not considered necessary to the health of amphibians that receive a Vitamin D3 supplement.

As with any amphibian, keeping the cage and the water bowl clean at all times is important. A frog’s permeable skin makes it highly sensitive to infection. I typically clean a simple enclosure once weekly.

Megophrys nasuta prefers moderate temperatures, typically in the range of 70 to 78 degrees Fahrenheit, and a humidity of 60 to 80 percent.

Natural Alternative

Designing a streamside naturalistic terrarium is an alternative approach to a simple enclosure. My Malaysian horned frog cages measure 45 inches long, 17 inches wide and 18 inches tall. Excessive height is not necessary because these animals are primarily terrestrial and rarely climb.

Naturalistic terraria have worked well for trios of two male Malaysian horned frogs and one female Malaysian horned frog, but a smaller terrarium is suitable for an individual or a pair. A 20-gallon breeder terrarium is a good starting point for a pair because it provides a larger footprint than a traditional 20-gallon terrarium. A good rule of thumb is to add 5 gallons of space per additional frog, but a larger cage is always better for these large, easily stressed frogs.

I use a false-bottom setup consisting of egg-cratelike material used in packaging fluorescent lighting fixtures. This material covers approximately half of the Malaysian horned frog terrarium base. Appropriately sized panels are pieced together with small cable ties to make a box. This acts as the drainage layer. The egg-cratelike material is overlaid with fiberglass screen, which prevents soil from falling through into the false-bottom area and thus impeding drainage.

Many substrates, including crushed coconut coir, sphagnum moss or natural soil, can be used. I use a modified version of the Atlanta Botanical Gardens mix. Two parts of a coco-fiber and orchid bark mix are combined with one part of an activated charcoal and peat moss mix. I leave out the two parts of crushed tree-fern fiber described by the Atlanta Botanical Gardens because this item may potentially harm Malaysian horned frog’s gastrointestinal tract.

Water 2¾ inches deep fills the space uncovered by egg-cratelike material. Filtered spring water, water aged in an open container for 24 hours, or water dechlorinated with AmQuel or a similar aquarium product are good water options.

A 3-inch-tall glass panel divides the land and water sections. It supports the substrate and prevents it from falling into the water section. An alternative approach to a glass barrier is to use large-grade aquarium gravel as the land section drainage layer. This eliminates the need for a glass divider and a false-bottom setup, which can be difficult to install and maintain.

Select hardy plants to add cover for the Malaysian horned frogs. Appropriate examples include Scindapsus and Philodendron species, and the bird’s nest fern (Asplenium nidus). Appropriate UV lighting, though not considered necessary for the health of amphibians, is required for the health of the plants in naturalistic vivaria.

Feed These Leaves

Once Malaysian horned frogs are settled in a new environment, feeding is rarely a problem. Megophrys nasuta accepts a variety of prey insects (including crickets, cockroaches, silkworms, king worms and waxworms) and the occasional small mouse. I primarily feed my frogs crickets due to the ease of obtaining and culturing them. I typically feed frogs three times a week and allocate approximately five feeders per frog.

As with any captive amphibian, insects must be properly gut loaded before being offered to Malaysian horned frogs. A variety of products are available at pet stores and online. Along with these nutrient-rich insect diets, it is important to provide moisture in the form of fruit and vegetable matter. I typically feed feeder insects carrots, sweet potatoes, zucchini, yellow squash, oranges, apples, or collard and mustard greens. Other fruits and vegetables can be offered, but minimize those containing high levels of oxalates, such as spinach and kale. Oxalates can bind calcium and prevent its absorption in a frog’s gastrointestinal system.

Vitamin and mineral supplements are important to amphibian health. Many supplements are on the market, and it is difficult to sort through them all. The key is to provide an appropriate source of calcium and Vitamin D3 when a source of UVB light is not provided. New evidence also suggests that pre-formed Vitamin A is an important component in the diet of developing carnivorous amphibians. The supplement Repashy Superfoods Calcium Plus ICB now provides a source of pre-formed Vitamin A. Dust insects with an appropriate vitamin and mineral supplement once a week.

I prefer to remove my Malaysian horned frogs from their naturalistic enclosures and place them in an empty plastic feeding container to prevent the ingestion of foreign material. In my experience, these frogs are explosive and indiscriminate feeders, and necropsies performed by my veterinarian have revealed a variety of foreign materials within the gastrointestinal tract. A separate feeding container also prevents the buildup of decaying insect material in the vivarium water. However, it is not necessary in simple enclosures with substrates such as paper towels or foam rubber.

Breed With Success

Breeding the Malaysian horned frog (Megophrys nasuta) in captivity has been achieved with some regularity in Europe, but this species is rarely captive bred in the United States. Records from Europe are well-described in literature, and there is one record of an individual that recently achieved captive reproduction in the United States.

The primary obstacle is obtaining healthy female Malaysian horned frogs. In the past, many distributors have offered “pairs” that often turned out to be males of differing sizes. When true females became available, they were often in poor health, undoubtedly the result of females being housed with larger numbers of conspecific males in peak breeding condition. However, in the past five years the condition of wild-caught females has improved.

It is important to provide a relatively cool and dry period for approximately one month before any breeding attempts. I typically reduce the temperature gradually to the low 70s (degrees Fahrenheit) and reduce the relative humidity to about 50 percent.

Following this period, simulated rainfall often encourages male Malaysian horned frogs to vocalize. It is best to synchronize artificial rainstorms with periods of low barometric pressure in order to more closely approximate a natural weather pattern. During this time, feed animals once a week, so they maintain their body condition and do not become emaciated. It may be beneficial to feed females more food at each feeding (10 to 12 crickets for adult frogs), but reduce the frequency of feeding to prevent disturbing the animals.

Click image to enlarge A simple cage setup for Malaysian horned frogs includes a plastic bin and top. Placing ventilation screening at the top of the enclosure prevents snout abrasions.

Malaysian horned frogs huddle in a simple setup with paper towels dampened with spring water. The water dish provides the amphibians with an opportunity to soak when needed.

Malaysian horned frogs are described as solitary breeders. It is unlikely that a higher ratio of males to females will increase breeding success. Spawning occurs one to three weeks after the initiation of simulated rainfall. Eggs are typically attached to the underside of a half-round of cork bark that forms a sort of cave over the water section. The white eggs are either suspended over the water or laid directly on the water surface.

Malaysian horned frog larvae hatch one week after spawning, and they begin feeding after 15 to 20 days. As filter feeders, the larvae possess a large upturned oral disc that allows them to eat food from the water surface. An appropriate diet for this stage includes pulverized fish food or a diet designed specifically for tadpoles that remain on the surface.

Kept at temperatures between 76 and 78 degrees, Malaysian horned frog tadpoles develop hind limbs in approximately 75 days. Swimming behavior then changes. The frogs remain at the bottom of the aquarium, and their mouthparts begin to regress.

Forelimbs emerge within the next few days. At this time the water level should be lowered to around 1 inch deep, and cork bark should be provided to allow the Malaysian horned frogs to readily exit the water. Roughly a half-inch long at metamorphosis, froglets can be housed in small storage containers, such as 15-quart Sterilite shoeboxes, with moist foam rubber as a substrate. It doesn’t take long before they’re adults. With optimal care, sexual maturity is attained at just under 1 year of age (Zimmerman, 1986).

The Honk Betrays

In nature the Malaysian horned frog inhabits the rain forests of southern Thailand, Peninsular Malaysia, Tioman Island, Singapore, Sumatra, Bintan Island, the Natuna Islands and all parts of Borneo. Occurring up to elevations of 3,280 feet, they are encountered primarily near small streams, and the males’ loud call, described as a metallic honk, often gives them away. Females are much more difficult to find. They spend the majority of their time hidden in leaf litter and do not produce vocalizations.

A Remarkable Amphibian

The Malaysian horned frog is truly remarkable in its appearance. I still remember my first encounter with this species at an expo in San Diego, Calif. One vendor had a large group available, and I was astonished by the diversity present within this single species. Each animal was unique in its coloration and pattern.

I continue to work with a large group of these astonishing animals. Malaysian horned frogs are undoubtedly one of my favorite anuran species. With proper care they can live more than six years in captivity. Captive longevity will undoubtedly increase as more captive-bred individuals become available in the hobby.

It would be nice if that happened. Although Megophrys nasuta is widely distributed in the wild, every effort should be made to establish Malaysian horned frogs in captivity in order to reduce collection pressure on wild populations.