Pacific Horned Frog

Pacific horned frog（圖片來源：Hasanahh，採用 CC BY-SA 4.0 授權）

The Pacific horned frog (Ceratophrys stolzmanni), also known as the Pacific horned frog, belongs to the family Ceratophryidae. This species is primarily distributed along the Pacific coasts of Ecuador and Peru, inhabiting dry scrublands, leaf litter forests, and open sandy environments. Its distribution is fragmented and increasingly impacted by human activity, leading to continuous habitat loss. As a result, it has become a rare species in the wild.

In nature, Pacific horned frogs spend most of their time buried underground or hidden within leaf litter, entering a dormant state. During the rainy season (approximately January to March each year), they emerge in large numbers following rainfall and rapidly breed in temporary shallow pools. This represents an explosive breeding strategy. Large numbers of males call at night after rain to attract females, and mating occurs on land or in shallow water, producing hundreds to thousands of eggs. Tadpoles develop rapidly, typically completing metamorphosis within 20 to 30 days, ensuring they leave before the water bodies dry out.

Adult frogs are characterized by a broad head and an exceptionally large mouth. Males measure approximately 4.8 to 6.7 cm in body length, while females range from 5.3 to 8.2 cm. This morphology allows them to consume prey up to one-third of their own body size. Their diet in the wild is highly diverse, including insects, spiders, snails, centipedes, and even small frogs, snakes, and rodents. Cannibalism and scavenging have also been documented.

Behaviorally, the Pacific horned frog is an ambush predator, remaining motionless while waiting for prey before striking and swallowing it whole. It is mostly inactive during the day, remaining buried, and becomes more active at night, though it still tends to remain sedentary. Adults possess well-developed tooth-like structures and may bite if handled roughly, potentially causing bleeding. Their lifespan in the wild is relatively short, typically around 3 to 4 years.

In South America, native populations of the Pacific horned frog are classified as Vulnerable by the International Union for Conservation of Nature (IUCN).

Housing Requirements in Captivity

In captivity, replicating the natural environment is essential. The Pacific horned frog originates from warm and relatively dry environments, so temperatures should be maintained at approximately 26 to 29°C, with a slight decrease at night. Sudden drops in temperature must be avoided to prevent shock. Temperatures below 24°C can impair digestion and activity, while those above 32°C may lead to overheating and dehydration. Relative humidity should be maintained between 65 and 75 percent and kept stable.

The enclosure does not need to be large for a single individual; a 40 × 30 × 30 cm glass or plastic terrarium is sufficient. However, a suitable substrate for burrowing must be provided. Materials such as sphagnum moss, coconut fiber, or leaf litter can be used, with a recommended thickness of 3 to 5 cm to allow burrowing behavior. A false bottom layer with water can help maintain humidity, but gravel or sand should be avoided, as accidental ingestion may cause intestinal blockage.

A shallow water dish or a thin layer of standing water (approximately 1 to 3 cm) must be provided for soaking, but it should not be too deep to prevent drowning. Water quality must be kept clean, and chlorinated tap water should be avoided. Water should be left to stand for 24 hours or treated with a dechlorinator. The enclosure should include hiding places such as leaf litter, bark, or stones to provide a sense of security.

Strong lighting is unnecessary, but low-level UVB lighting can be provided to support calcium metabolism. Adequate ventilation is required to prevent mold growth.

Due to their cannibalistic tendencies, multiple individuals should not be housed together unless for breeding purposes.

Pacific horned frog（圖片來源：Loïc Denès，採用 CC BY-NC-SA 2.0 授權）

Feeding Conditions

The Pacific horned frog is known for its large appetite, but feeding must be controlled in captivity to prevent obesity and metabolic disorders.

Recommended food items include earthworms, mealworms, superworms, silkworm pupae, and crickets. Occasionally, small pieces of fish (such as tilapia fillet) or formulated diets may be offered. Feeding live fish or mice is not recommended, as it may lead to excessive fat intake or digestive issues. If used, they should only be offered occasionally.

Food should be offered using long feeding tongs. Gently moving the prey near the frog's mouth can simulate live movement and trigger feeding behavior. Live insects should not be released directly into the enclosure, as they may hide or injure the frog.

Adults should be fed once every 5 to 7 days, with prey items approximately one-third of the frog's body length. Juveniles grow rapidly and may be fed every 2 to 3 days. Overfeeding can result in obesity and reduced lifespan. Uneaten food should be removed promptly to prevent decay and bacterial growth. If a frog refuses to eat, it is usually related to improper temperature or humidity, and environmental conditions should be checked first.

Breeding Conditions

Breeding in captivity is difficult and requires simulation of the rainy season. Adults should typically be housed separately until reaching sexual maturity (around 1 year of age). During the breeding period, males and females can be introduced into a breeding tank with a shallow water layer of approximately 5 cm.

Water temperature should be maintained at 27 to 29°C, and rainfall can be simulated using misting. Males will call at night and engage in amplexus with females.

If successful, females may lay several hundred to over two thousand eggs. The eggs require gentle water movement and aeration. They hatch into tadpoles after approximately 40 hours and complete metamorphosis within 20 to 32 days. Each tadpole should be raised separately to prevent cannibalism and fed high-protein tadpole diets, algae, or finely chopped insects.

For non-professional keepers, intentional breeding is generally not recommended, as it requires significant space, water management, and individual rearing. Without proper care, tadpoles may die rapidly or consume each other. If breeding occurs unintentionally, it is advisable to transfer some eggs to professional breeders, experienced keepers, academic institutions, or animal care organizations to avoid being overwhelmed by large numbers of offspring.

Preventing Invasive Spread

Due to its strong predatory behavior and adaptability, the Pacific horned frog may pose a threat to local ecosystems if released into the wild. It is capable of consuming other amphibians or reptiles of similar size, and even small birds or mammals. Once established outside its native range, it has a high potential to become an invasive species.

Owners must never release individuals into the wild, regardless of their health condition. Animals should be cared for throughout their lifespan. If unable to continue keeping them, owners should seek qualified animal shelters or experienced keepers for rehoming. Breeding should be avoided unless necessary and carefully planned, as hundreds of tadpoles may otherwise have no proper placement.

Keepers should also recognize that this species is classified as Vulnerable in the wild. When acquiring individuals, captive-bred specimens should be chosen, and wild-caught individuals from South America should be avoided to prevent contributing to overcollection of native populations.

Author: Shui-Ye You