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Habitat Parameters

Providing the proper habitat to house Leafy seadragons is one of the most important elements in their husbandry. Key factors such as system design, water flow, temperature, and lighting are critical to the well being and long term health of the Leafy seadragon (Powell 1997).

System Design

The size of the aquarium housing Leafy seadragons is important in several ways. The length and width must be such that the animals have plenty of space in which to swim, without being crowded. Leafy seadragons can easily damage their slender snouts, if accidentally pushed by a tank mate or the current into the sides of the exhibit. In general, the Leafy seadragon also seems to prefer a deep aquarium as opposed to a shallow aquarium, which is also beneficial when displaying the fish in an exhibit with either live or artificial kelp. The depth of the aquarium can also aid the newly acclimated Leafy seadragon in regaining its buoyancy (Groves 1997). It is very common for the Leafy seadragon to experience buoyancy problems during or shortly after collection and transport. In many instances, this tendency to float at the surface can be corrected by the seadragon itself when placed in a deep tank. The inability to correct a buoyancy problem, can ultimately lead to the death of the animal.

Leafy seadragons have been displayed in a variety of exhibits with success in terms of their longevity. Most of the successful exhibits have been at least one meter or more in height and width. Recently, seadragons have also been displayed in cylindrical exhibits (Marshall 2004). Table 2 (See Syngnathid Husbandry Manual) is an excerpt from a paper presented at the AZA National Conference in Minneapolis, Minnesota in 1999 describing the size of the exhibit and relation to the observation of breeding behavior in Leafy seadragons. Since 1999, many of these institutions, as well as a number of others have experienced repeated egg production events, without successful transfer of eggs to the male. The reasons for these failures are still unknown. Exhibit design, especially tank depth may eventually prove to be a factor in successful breeding of Leafy seadragons (Powell 1999).

Holding or quarantine systems should be designed to accommodate the animals at various sizes, but especially when the animals are young and quite small.

Water Flow and Temperature

Depending on the size and volume of the exhibit or holding system, the flow should allow the entire volume of the aquarium to be turned over at least 4-6 times per hour. At The Dallas World Aquarium, we use two ¾ horse power spa pumps to circulate water through a reservoir (sump) and to the exhibit. Too little flow will result in a reduction of activity of the seadragon; too much flow can cause them to “fight” the current, potentially exposing the fish to undue stress as well as injury. In an effort to help prevent piping behavior at the surface of the aquarium, it is best to keep a little flow across the top to disrupt the “mirror” effect that can occur with a lack of flow at the surface (Delbeek 2005).

Water temperatures in the natural range of the Leafy seadragon range from 9 degrees C to 21 degrees C. Generally, seadragons are kept at temperatures between 12 degrees C and 18 degrees

C. A number of institutions have been varying their temperatures in order to initiate breeding (Forsgren 2004). A Universal Marine Titanium chiller is used for maintaining water temperature in the seadragon exhibit at The Dallas World Aquarium.

Filtration

Filtration for Leafy seadragon displays can be achieved in a number of different ways. At The Dallas World Aquarium, our seadragon display and holdings are very simple closed systems. Synthetic seawater is made using the city water supply, filtered by reverse osmosis and Instant Ocean salt mix. Biological filtration is achieved using a “modified Berlin” method with live rock as the only biological filter. A large “ETS” style protein skimmer, Baker Hydro mechanical pool filter and Rainbow/Lifeguard UV sterilizer are used for water clarity. Super activated charcoal and Aquarium Pharmaceuticals phosphate remover are used as chemical filter media. Ozone use is not recommended on a Leafy seadragon exhibit.

Water Quality and System Maintenance

In order to ensure that Leafy seadragons remain healthy and disease free, excellent water quality is required. Frequent, small, water changes, with siphoning of the substrate, is recommended. These water changes should be done with a minimum of stress to the dragons, with little or no temperature or salinity change. Removing the dragons to siphon the exhibit is not recommended. Water quality parameters should not vary to any great degree. Below is a description of the acceptable parameters for water quality in the seadragon exhibit at The Dallas World Aquarium.

Salinity: 27 – 35 ppt Nitrate (NO3) < 5.0

pH: 8.0-8.3 Phosphate ( PO4): <0.05

Ammonia (NH3): 0.0 Calcium 250-400 ppm

Nitrite (NO2): 0.0

Lighting requirements

Seadragon in dimly lit display.

Lighting a Leafy seadragon display is one of the most important factors in successfully maintaining the collection. Sudden, dramatic changes in lighting are a source of stress to the Leafy seadragon. A variety of lights should be used so that the seadragons are exposed to a varying amount of light, gradually increasing throughout the day, and decreasing at night. Paul Groves, formerly of Underwater World, Perth Australia (Groves 1996), discourages the use of intense lighting normally used to light coral reef displays, as this is, in his opinion, too intense for the Leafy seadragon. At The Dallas World Aquarium we now use only one 250 watt metal halide light, and have not observed that this is a problem for the seadragons. One problem that does result from the use of metal halide lighting is the growth of filamentous algae, which can cause the seadragons to become entangled when feeding. The combination of metal halide and fluorescent actinic lighting is very effective for both display and husbandry purposes.

The use of a night light has also been important in the lighting requirements of the Leafy seadragon at The Dallas World Aquarium and many other institutions displaying seadragons. We use a small 20 watt fluorescent tube that is timed to come on just before the main exhibit lights go out for the day, and will go off, just as the main lighting is beginning to come on. We have observed that the seadragons tend to be attracted to external light sources outside of the exhibit and gather near the front of the aquarium when the “night light” is not on above them. They appear more settled, and will group together in a cluster when the light is in use.

Many institutions are varying their light cycles, naturally or intentionally, in order to help initiate breeding. In some instances, this variation coincides with the fluctuations in temperature to simulate the changes in sunlight and water temperatures in their natural environment (Forsgren 2004).

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This entry was posted on Friday, May 29th, 2009 at 7:00 am and is filed under Advanced Care. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.