Pygmy Horses in My Living Room

by John Manrow
First published in The Fish Flash, Greater Portland Aquarium Society, May 1998
Aquarticles

There has been quite an increase in the number of requests for information on seahorses lately, particularly the pygmy or dwarf seahorse, Hippocampus zosterae. This may be due to the May 1998 issue of TFH magazine, which contained three related articles. This article is about some of my experiences over the years keeping this unusual fish.

It was because of my desire to keep living seahorses that I set up my first saltwater aquarium in 1969. I used a plastic 10 gallon tank with a Metaframe Hi-Fi undergravel filter and silica sand as a substrate. After setting up the tank, I added two bags of Rila saltwater mix, enough for 10 gallons of artificial seawater mix. I allowed the tank to run at the specific gravity of 1.025 for a week before purchasing a pair of large Atlantic seahorses, Hippocampus erectus, for $3.95 apiece. This seemed a high price for me to pay, since neon tetras sold eight for a dollar at the time.

The seahorses took immediately to their new home, swimming about, snapping up live brine shrimp, which I was already buying for my freshwater fish every Tuesday for $.35 a portion (those portions seemed a lot larger than what we are getting now, and actually seemed to last a week!). At the time I was still living with my parents just a few miles from the salt ponds where the brine shrimp were harvested.

All was going well with seahorse keeping until suddenly no live shrimp were available. I was told it was because of heavy rains, so I tried frozen brine. The seahorses were very hungry by this time. They would follow a dead brine shrimp, and when it was realized it wasn’t moving, interest was lost in the shrimp. Then another shrimp would be followed with the same result. When live brine was available a few weeks later, it was too late. The two seahorses starved, rather than eat non-living food. I had read the booklet "Keeping Seahorses" by Robert & P.L. Straughan over and over, but was not prepared for running out of live food. Now I had two dried seahorses and moved on to keeping other tropical marine fish and invertebrates. I decided that if I couldn’t provide proper food for a fish, I wouldn’t attempt to keep it. I did occasionally order seahorses for customers when I entered the pet trade in 1974, but it wasn’t until I set up my first mini-reef in 1986 that I found the seahorse to thrive. In the presence of live rock and full spectrum lighting, there was an abundance of marine life - copepods, rotifers, and amphipods - to supplement the diet.

About ten years ago I ordered six pair of H. zoster (dwarf seahorses) from Aqualand Pets in Florida. They arrived in the mail a few days later. I had a 15 gallon tank with two 40 watt full spectrum fluorescent lights. I use Penn Plax undergravel filters with modifications. One of the adjustable lift tubes remains in the corner modified into a co-current protein skimmer, while the other u/g plate is positioned so the lift tube is situated at the back center of the tank. The lift tube extends above the water surface. The Marineland P110 Penguin filter with Bio-Wheel was used with the intake tube inserted in the u/g lift tube. This allows water to be drawn from the aquarium without filtering out the brine shrimp nauplii fed to the dwarf seahorses. The substrate consisted of a crushed coral-live sand mixture. There were four or five Florida plant rocks with heavy growth of Caulerpa spp, Halimeda, Acetabularia, and other macro-algae.

About three days after receiving the shipment of fish, a male delivered about thirty seahorse larvae, complete with prehensile tails! I had two hatching jars for brine shrimp which I started on alternate days, so I have newly hatched nauplii every morning. I decapsulate the brine shrimp cyst before hatching for increased hatch and ease of harvesting. I found the gestation of dwarf seahorses to be ten days. After delivery the male will sometimes be seeking out a gravid female to deposit more eggs in his breeding pouch. Prior to spawning the pair will quiver rapidly. The male inflates his brood with water. The pair then release from their holdfasts and meet in the water column. Their tails intertwine, the female inserts her ovipositor and transfers the eggs into the male’s pouch, where they are fertilized internally. As I mentioned before I had six pair to start with and ended up with hundreds. I seems that if dwarf seahorses have a continuous (and I mean continuous!) supply of food, there is no stopping them from reproducing.

After the larvae were delivered, they were transferred by the means of a 5/16" diameter, 12" long rigid plastic dip tube to a 10 gallon rearing tank, also heavily planted. Providing food for the young would be much easier with rotifers until about 3 or 4 weeks old, then feeding brine shrimp nauplii.

At the time I was not involved with GPAS, and could not find many people willing to hatch brine shrimp eggs to properly feed them. When a store was found willing to take them, I traded my remaining stock, along with a pair of Hippocampus ingens and some shrimpfish for test kits and books.

For the year or so that I kept these little guys it was quite an adventure, but providing a constant supply of newly hatched brine shirmp was preventing a trip out of town for more than twelve hours - impossible for me at the time.

If you are interested in giving dwarf seahorses a try, I feel it will be a very exciting and rewarding experience. My advice is to acquire only one or two pairs, have a rotifer culture going, and some plants and rocks in the aquarium.

An excellent source for purchasing dwarf seahorses is Aqualand Pet Center, PO Box 55-7365, Miami FL 33255-7365.

Information on the Internet:

Seahorse Research Society: http://members.aol.com/gatesma/private/Seahorse/index

Project Seahorse: http://www.ayware.co.uk/seahorses/index.htm

Aquatic Bookshop: http://www.seahorses.com

Breeders Registry: http://www.breeders-registry.gen.ca.us/database/HIPZOS02.htm