The Redspot, Dwarf, or Parvulus Cardinalfish (Apogon parvulus) is found throughout the Western Pacific. It reaches a maximum size of about 1.5” in the wild, about 1” in captivity, and sports an unmistakable red spot at the base of the caudal fin in contrast to its striped silver and blue body. These tiny cardinalfish seemed to be perfectly suited for aquariums and would get along well in captivity.
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Like so many other marine ornamental fish, the ultimate state of health in the Parvulus Cardinalfish in captivity depends a great deal on how they are held and handled during the chain of custody from the tropical Pacific to a fish store near you. With proper handling and conditioning, and holding them with small, less active and passive fish and with intensive conditioning for a few weeks, they are rock solid fish.
Parvulus Cardinalfish is relatively straightforward to acclimate and keep healthy in a reef aquarium. They are found in the tropics in shallow water, so typical salinity and temperature in a reef aquarium will suit them fine. They easily adapt to a wide range of lighting and flow conditions.
The significant challenge is getting them to eat prepared foods and feeding them a few times throughout the day. For the first 1-2 weeks, Parvulus Cardinalfish may need to be coaxed to eat with live baby Artemia, Daphnia, Tigger-pods, and rotifiers, or frozen Cyclop-eez and Arcti-pods. Good secondary foods to try are small Hikari mysis shrimp, and fish, prawn, lobster, or oyster eggs. In just a few weeks you Parvulus Cardinalfish should be reliably eating small pellet food. It is important to feed your Parvulus Cardinalfish a few times, throughout the day.
Because of their tiny size Parvulus Cardinalfish are potential prey items for a wide variety of tankmates. Hawkfishes, wrasses, dottybacks, basslets, and even larger cardinalfishes may snack on them if the size difference between predator and prey is large enough. Aside from very tiny crustaceans, you don’t have to worry about Parvulus Cardinalfish bothering much in your reef aquarium. Newly added sexy shrimp (Thor amboinensis) and very tiny gobies may be consumed by adult Parvulus Cardinalfish.
If fed well and housed with tankmates that don’t harass them, Parvulus Cardinalfish may spawn regularly. Like all cardinalfish they are mouthbrooders; the male holds the eggs in his mouth until they are ready to hatch. There are no apparent external differences between the sexes, but males should be recognizable from their mouthful of eggs. The larvae are particularly small and may prove to be much more difficult to rear than some other Apogon spp. which have been reared successfully in captivity.
