Seadragon husbandry techniques
at the Oceanário de Lisboa
Techniques de maintenance des dragons de mer
à l’Oceanário de Lisboa
E. SANTOS1, G. NUNES1, N. PEREIRA1, J.F. PEREIRA1, M. F. L. SMITH2
1
Oceanário de Lisboa, Doca dos Olivais, Pt-1990-096, Lisboa, Portugal
2
Oceanário de Lisboa / IDEA Inc., Doca dos Olivais, Pt-1990-005,
Lisboa, Portugal
ABSTRACT
Leafy seadragons (Phycodurus eques Günther, 1895), and weedy seadragons
(Phyllopteryx taeniolatus Lacépède, 1804), are two of the most beautiful and
spectacular representatives of the Syngnathidae family. They represent extremely
popular and yet very sensitive animals for exhibits.
Oceanário de Lisboa has maintained leafy and weedy seadragons since April 1998.
This article summarizes the captive husbandry of seadragons maintained at the
Oceanário de Lisboa, with specific reference to the following: (i) life history; (ii) life
support systems; (iii) exhibit maintenance; (iv) water quality; (v) nutrition and feeding
techniques; (vi) captive behaviour; (vii) pathology; and (viii) captive reproduction.
RÉSUMÉ
L’hippocampe feuille (Phycodurus eques Günther, 1865), et le dragon de mer
commun (Phyllopteryx taeniolatus Lacépède, 1804), sont les deux plus belles espèces
de la famille des Syngnathidés. Ces animaux, exposés en aquarium, sont très populaires
auprès des visiteurs, mais sont des espèces très sensibles et délicates.
L’Oceanário de Lisboa présente des dragons de mer et des hippocampes feuilles
depuis avril 1998. Les procédures zootechniques pour la maintenance en aquarium de
ces Syngnathidés sont discutées ici, spécialement dans les domaines suivants : (i) le
comportement naturel; (ii) les installations techniques et les systèmes de maintenance ;
(iii) l’aménagement intérieur de l’aquarium; (iv) la qualité de l’eau; (v) l’alimentation et
les techniques de nourrissage; (vi) le comportement en captivité; (vii) la pathologie ;
(viii) la reproduction en captivité.
Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
INTRODUCTION
Both the leafy seadragon (Phycodurus eques Gunther, 1865) and the weedy
seadragon (Phyllopteryx taeniolatus Lacépède, 1804) are normally found
associated with a partially rocky substrate with abundant algae. They prefer
areas with sargassum, kelp or seagrasses (Groves, 1996).
Their favourite prey is mysid shrimp and other small benthic crustaceans.
Being extremely well camouflaged, seadragons use the element of surprise to
attack their prey (Mackay, 1995; Kuiter, 1996).
The female seadragon produces approximately 420 eggs with a diameter of
3.0 mm. Only about 250 eggs, however, are transferred to the male for
fertilisation and incubation. During incubation, the male seadragon carries the
eggs underneath his tail for around 8 weeks. Hatching of the eggs usually takes
about 1 to 2 weeks. The juveniles are immediately independent of the adults and
start feeding on small mysid shrimp 2 to 3 days after their birth (Mackay, 1995;
Groves, 1996; Kuiter, 1996; Powell, 1997).
METHODS
The Oceanário de Lisboa has two tanks dedicated to maintaining seadragons,
a quarantine / isolation tank and an exhibition tank. The water-treatment and
life-support systems of these tanks have been summarised and are represented in
Table 1.
Water quality parameters are analysed and recorded daily. Water quality
parameter ranges have been summarised and are represented in Table 2.
In accordance with these animals’ high sensitivity to environmental changes,
very strict daily maintenance routine of these tanks is required. Tanks are
vacuumed every day, representing a 1.0-2.0% daily water exchange. An
additional 5.0% water exchange is performed each week. Mechanical cartridge
filters and activated carbon are replaced each month and UV lamps are replaced
biannually.
The seadragons are fed 2 to 3 times daily with frozen mysid shrimp. We have
chosen to use frozen mysids as the sole source of food for a number of reasons.
They include: (1) reduced labour for culturing and maintaining live mysids; (2)
reduced risk of contamination by infectious agents (e.g. protozoa, bacteria, etc)
that may be introduced with the live food; and (3) enhanced ability to count the
number of food items consumed by individual seadragons.
Training the seadragons to accept frozen mysid shrimp was challenging. It
was achieved by placing a water inlet on the bottom of the tank that consisted of
Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
an upward-facing perforated manifold. This manifold created gentle up welling.
Frozen mysid shrimp were injected into the water column where the up welling
caused the shrimp to ‘swirl’ around in a manner similar to ‘swimming’
behaviour. This attracted the seadragons’ interest. The up welling also kept the
mysids suspended in the water column for longer periods, allowing the
seadragons time to ‘capture’ their prey. Initially, both live and frozen mysids
were introduced in this manner. Over time, the live mysids were ‘phased out’,
until only frozen mysids were routinely introduced.
RESULTS AND DISCUSSION
During the first two years of operation, 6 of the 12 seadragons maintained at
the Oceanário de Lisboa were lost. Losses were principally due to a protozoan
(Uronema sp.) infestation complicated by a bacterial infection (Vibrio
vulnificus). Uronema sp. is a free-living facultative parasite, which is highly
invasive when the host is stressed. The observed external symptoms were
anorexia, lethargy and cutaneous lesions.
It was considered that environmental stress may have made the seadragons
more susceptible to infectious agents. As a consequence, improvements were
made to the water-treatment systems (esp. UV implementation), daily
maintenance routine and feeding regime. This appeared to arrest the problem of
infectious agents.
The behavioural repertoire of the seadragons maintained at the Oceanário de
Lisboa has been summarised and is represented in Table 3. Several egg-laying
events occurred. Observed behavioural and morphological changes during egglaying activity have been summarised and are represented in Tables 3 and 4,
respectively.
Egg-laying activity seems to be subject to rather precise periodicity. This is
evidenced by the last six egg-laying events displayed by a pair of leafy
seadragons, whereby egg laying occurred at 101.8 ± 1.7 (n = 5) day intervals
(Figure 1).
ACKNOWLEDGEMENTS
The authors would like to thank the following people for their continued
advice and assistance: Chris Coco, Charles Delbeek, Paul Groves, Annelisa
Kilbourne, Bruce Mackay, Paula Powelle and Darleen Walder.
Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
REFERENCES
GROVES P., 1996.- Recent advances in the captive husbandry of seadragons
(Phyllopteryx taeniolatus and Phycodurus eques). Personal commun.
KUITER R., 1996.- Guide to sea fishes of Australia. New Holland Publishers,
London. 433 pp.
MACKAY B., 1995.- Seadragons in wild and captive environments. Today’s
Aquarist, 7 (1).
POWELL P., 1997.- The care and husbandry of leafy seadragon, Phycodurus
eques. AZA Annual Proceedings, 440-446.
Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)