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Related Articles: The Genus Chaetodon

/The Conscientious Marine Aquarist

The Lemon or Milletseed Butterflyfish, Chaetodon miliaris; Still Legal and Still a Treasure

Bob Fenner


Butterflyfishes for Marine

Diversity, Selection & Care
New eBook on Amazon: Available here
New Print Book on Create Space: Available here

by Robert (Bob) Fenner

A not uncommon site in Hawai’i’; a crowd of fishes following a diving group, hoping for discovered food items. Here in Molokini Crater off Maui there’s almost always a mob of Milletseeds. Here also you can see another Hawaiian endemic; the Saddle Wrasse; Thalassoma duperrey, also still legal to collect.


 With the advent of the US 50th State’s efforts at conserving fish stocks on its limited shallow shores, some forty species have been set aside as “to catch” with the remainder being off limits to ornamental marine collectors. I personally have misgivings re the inclusion of some (e.g. the Fourspot, Chaetodon quadrimaculatus) as it has a dismal survival record in captivity; and am guarded re some species that have been disallowed. What is worse in my opinion is the issuance of too many licenses, allowing for casual collectors to join the trade…. Be all this as it is, the law is the law; and am glad as an olde timey fisheries student to see some action being taken to control the take in Hawaiian waters.


Identification, Some Systematics:

            Mmm; the Milletseed is a Butterflyfish, family Chaetodontidae; one of one hundred twenty nine valid species arrayed in twelve genera (currently; according to Fishbase.org). Chaetodon miliaris is one of four endemic (found nowhere else) butterflies, of about twenty five total found in the Hawaiian Islands; but amongst the entire family it is unmistakable. With a black band through the head and eye, prominent dark spot on the caudal peduncle (that part of the body right before the tail fin), pleasing warm yellow body and tail color speckled with vertical rows of stippling dots (the millet seeds thus named).

A younger (4” overall length) and older/larger (about 5” TL) Lemon B/F off the West coast of Kona, Hawaii’s Big Island. To 6.5 inches length maximum.



            Like all Butterflyfishes the lau wiliwili (Hawaiian name; lauhau for many Butterflyfishes there, and shaped like and the color of the fallen leaves of the wiliwili tree) spends all daylight hours scrounging about midwater and near the bottom for food. This species is a generalized zooplanktivore, but it will pick out small mollusks, worms and more from substrate and amongst stony corals. This fish is NOT a corallivore however; and unless really starved does not ingest live coral polyps for nutrition.

            During evenings the Milletseed hunkers down hiding under cover of rock caves and overhangs, doing its best to avoid predators; remember, Hawaii is the “land of the puhi” (eel), with Morays making up more than half reef fish biomass.

            Oh, and as young up to mid-size, the Milletseed is a facultative (non-obligate) cleaner of parasites off other fishes; even picking at turtles cruising by.


            C. miliaris gets along with all other than small food organisms; the reverse cannot be stated however. The usual suspects: large basses, big wrasses, over-size angels, the larger puffers and triggers, aggressive tangs and territorial damsels… can work them woe. Best to introduce this and all other Butterflyfishes in advance of any questionable tankmates; to give them time to adjust, learn the “lay of the tank”.

            In hobbyist sized systems; best to keep just one specimen to a tank; but if trying two, or more in a system of hundreds of gallons, introduce all at the same time to reduce the chance of territoriality.


            Careful observation of Butterflies includes close inspection of the body, especially the mouth. Chaetodontids mis-shipped in too small a bag with too little water, often suffer from rubbing their faces; damaging their mouth. Such damage often spells doom for the fish, negating feeding behavior, leading to decline and death.

            Beyond snapshot looking, you should spend some time watching the interpersonal and feeding behavior of a specimen you’re interested in acquiring. Make sure the animal is outgoing and seeking, accepting the types of foods you’ll be offering.


            Like all Butterflyfishes, the Milletseed needs space; to forage, move about, and to feel secure. I would NOT place a Chaetodontid in anything smaller than a five foot long, one hundred gallon system.

            Where do they live? On and above the reef; so they need reef-like water conditions. A paucity of accumulated metabolite (less than 10 ppm NO3 e.g.), high dissolved oxygen (from vigorous skimming perhaps), complete and brisk water movement (ten-twenty times turnover per hour); high and stable pH and alkalinity…


            The very best arrangement for supplying zooplanktivores in captivity is having a large, vigorous tied in living sump; yes, a refugium; with a big and deep sand bed of fine carbonaceous sand, culture of macro-algae, and if possible, on a reverse daylight photoperiod (RDP) arrangement.

            Barring this, providing minced or whole/small meaty sea life (e.g. Mysis, Copepods…) a few times daily will keep your Butterfly in good stead. Soaking such food in a vitamin, HUFA, pro-biotic supplement once or twice a week will go a long way to sustaining health and color.


            Butterflyfishes as a group are notoriously touchy; often being the first to show signs and perish when environment degrades or pathogenic disease appears. The Milletseed is on the far positive side of this scale at least; and you can usually count on observing it for evidence (lack of feeding, reddening near fin spine origins, heavy breathing; shyness…) for the beginning of trouble.

            Improving environment and nutrition are the best means of assuring health; but the use of quinine compounds (Chloroquine Phosphate a fave) is of use in curtailing most Protozoan complaints.


            This species is oviparous (egg laying), egg-scatterer; pelagic spawner with young developing as plankton; form temporary pairs seasonally. As far as I’m aware, it has not been spawned, reared in captivity.



            The Milletseed is Hawaii’s most common Butterflyfish, and though it’s not widely used in the hobby, it is a superlative captive species; hardy, beautiful and despite its little pointed mouth, a good shipper and eater of a wide range of readily available foods. If you’re shopping for a good mid-sized fish for a peaceful fish only, fish only with invertebrate, or full blown reef set up; I strongly urge you to consider Chaetodon miliaris. For folks angling for a Hawaiian biotope, for sure I’d include this species.

            Fishbase points to this species high resilience, with a doubling rate/time of some fifteen months; the Lemon Butterfly is not only aquarium desirable, but plentiful in the wild.

Some verticals for your consideration:



Bibliography/Further Reading:

http://www.fishbase.org/summary/FamilySummary.php?ID=343; Family Chaetodontidae on Fishbase.org

http://dlnr.hawaii.gov/dar/files/2014/05/WHI_Aquarium_Background.pdf ,
Walsh, William J., 2013. Background Paper on West Hawai’i’ Aquarium ‘White List’. Hawai’i’ Division of Aquatic Resources.

Waikiki Aquarium’s online spiel re this species


Butterflyfishes for Marine

Diversity, Selection & Care
New eBook on Amazon: Available here
New Print Book on Create Space: Available here

by Robert (Bob) Fenner
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