A 4g wouldnt be big enough dog face get to 6" in size you could go for the smaller version fire bellied newts.Below is a caresheet for Dog face
Common Name: Hong Kong Warty Newt, Giant Fire-bellied Newt, Dog Faced Newt.
Scientific Name: Paramesotriton hongkongensis.
Distribution: Hong Kong.
Size: 14-16cm.
Sexing: Males have more swollen cloaca. Females are often plumper when viewed from above.
Description: Smoothish light - dark brown or olive skin with a bluish black colouration to the underside of the body marked with irregular yellow-orange markings.
Requirements: Mainly aquatic and require a relatively small aquarium. A 15-gallon tank would be adequate for an adult pair. These Newts can be maintained in a totally aquatic set-up, provided they have a few floating islands (pieces of cork) to climb out on to. A base substrate of gravel or sand is ideal with large pebbles and lots of aquatic plants arranged to provide a number of hiding places. The water should be clean de-chlorinated or spring water at a depth of 20cm (8"). partial water changes should be carried out at regular intervals. It is also a good idea to lightly oxygenate the water with the use of an air-stone. A water temperature of 20-22°C should be maintained, and low wattage fluorescent tube should be used as a light source.
Feeding: Juvenile Newts should be fed daily with a mixture of suitably sized insects including bloodworm, Tubifex, and whiteworm. Adult Newts should be fed every other day with a mixture of earthworms, slugs, maggots, and Tubifex