Argentine Horned Frog

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

The Argentine horned frog (Ceratophrys ornata), also commonly known as the Argentine horned frog or wide-mouthed frog, is famous for its round body and an enormous mouth that occupies nearly half of its body length. Its appearance resembles the classic video game character Pac-Man, which is why it is widely referred to as a pacman frog in English. This species is native to South America, primarily inhabiting grassland regions of Argentina, Uruguay, and Brazil. It is a terrestrial amphibian that moves slowly but is well known for its aggressive predatory behavior.

In the wild, Argentine horned frogs typically remain buried in leaf litter or soil, exposing only their eyes and upper body while waiting in ambush. When prey approaches, they lunge suddenly with remarkable speed. Their diet is extremely opportunistic, consisting of almost anything they can swallow, including insects, spiders, lizards, other frogs, birds, and even small mammals. They may attempt to consume prey larger than themselves, a behavior that highlights their bold and voracious nature.

Their thick, robust bodies allow them to store fat reserves, which serve as an energy source during periods of drought or food scarcity. In natural habitats, they survive dry seasons by burrowing or remaining dormant, becoming active again when environmental conditions become moist. Wild individuals typically live for 6 to 7 years, while well-maintained captive individuals can exceed 10 years.

In terms of appearance, they are commonly bright green with red markings, though variations include brown, dark green, or reddish base colors with darker patterns. Selective breeding in captivity has produced additional color morphs such as albino and strawberry forms. Females are generally larger than males, reaching over 16 cm in body length, while males are usually around 11 cm. Mature males develop a darker throat coloration and keratinized structures on the inner forelimbs known as nuptial pads, which help them grasp females during breeding.

Individual with different color morph（圖片來源：PEAK99，採用 CC BY 3.0 授權）

Housing Requirements in Captivity

Argentine horned frogs require a horizontally oriented enclosure due to their terrestrial lifestyle. A tank with a secure lid is recommended, with sufficient floor space rather than height. The substrate should retain moisture while allowing burrowing, such as coconut fiber or soil-based mixtures, with a depth adequate for partial burial.

Humidity should be maintained at a moderate to high level, typically between 60% and 80%, while ensuring proper ventilation to prevent mold growth. Temperature should be kept between 24 to 28°C during the day, with a slight drop at night. A shallow water dish must be provided for soaking, but it should not be deep enough to risk drowning.

Hiding spots such as cork bark or leaf litter help reduce stress. Lighting does not need to be intense, but a natural day-night cycle should be maintained. UVB lighting is optional but may support overall health when used appropriately.

Typical habitat（圖片來源：David J. Stang，採用 CC BY-SA 4.0 授權）

Feeding Conditions

Argentine horned frogs are extremely voracious, but uncontrolled feeding can quickly lead to obesity and reduced lifespan. Feeding should be carefully managed and adjusted according to age.

1. Juveniles

Newly hatched or small individuals should be fed small live insects such as crickets and mealworms. Feeding should occur daily. Calcium and vitamin D3 supplements should be added at least two to three times per week to support proper bone development.

2. Subadults

During the growth phase, feeding can be reduced to once every 2 to 3 days. Diet can expand to include larger insects, earthworms, and occasionally small fish. Overfeeding should be avoided to prevent nutritional imbalance or digestive issues.

3. Adults

Adult frogs can consume small mice or pinky mice, preferably frozen-thawed for safety. However, rodents should not be the primary food source, as excessive fat intake may lead to obesity, blindness, or death. A balanced diet should consist mainly of earthworms, crickets, and large insects, with small rodents or fish offered once or twice per week. Typically, feeding every 5 days is sufficient, with adjustments based on body condition.

Feeding tools such as long tweezers or feeding tongs are recommended to prevent accidental bites. Argentine horned frogs have strong jaws and bony projections within the mouth, making their bites painful.

Breeding Conditions

In the wild, breeding is triggered by the rainy season. Males call near water bodies to attract females. During mating, males use their nuptial pads to grasp females in amplexus. A single female can lay approximately 2000 eggs, which hatch into tadpoles within about two weeks. Tadpoles grow rapidly and exhibit strong cannibalistic tendencies, resulting in low survival rates in natural environments.

Successful breeding in captivity is challenging and usually requires simulating a dry season followed by a wet season. This involves lowering temperature and humidity for a period, then introducing high humidity and abundant water to stimulate spawning. After eggs are laid, adults should be separated immediately, as they may consume both eggs and tadpoles. Tadpoles require frequent and abundant feeding, such as chopped earthworms, brine shrimp, or daphnia.

Without sufficient experience and proper equipment, breeding is not recommended. A successful breeding event can result in hundreds of offspring, requiring significant resources and planning. If breeding is intended, arrangements should be made in advance with pet stores or wholesalers to ensure proper placement.

Preventing Invasive Spread

Outside of South America, Argentine horned frogs are non-native species. If released or abandoned, they may pose a threat to local ecosystems. Due to their highly opportunistic feeding behavior, they can prey on a wide range of native small animals, potentially disrupting ecological balance.

There are already documented cases of invasive amphibians and reptiles, such as the American bullfrog and green iguana, causing significant ecological damage in various regions. Argentine horned frogs carry similar risks. Therefore, keepers must strictly adhere to a no-release policy. If they can no longer care for the animal, it should be rehomed responsibly or transferred to appropriate organizations rather than being released into the wild.

Additionally, keepers should avoid purchasing wild-caught individuals from South America. Most specimens available in the market are captive-bred. Choosing animals from reputable breeders or pet stores helps prevent the overexploitation of wild populations.

Author: Shui-Ye You