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Cold Water Catalina Gobies

Posted on Tuesday, February 9th, 2010 at 2:32 am by

There has been a lot of focus lately on sustainable aquarium livestock harvesting and responsible aquarium keeping. The Catalina Goby, Lythrypnus dalli, is one fish notorious for being kept in inappropriate captive conditions.

For years Catalina Gobies were marketed as tropical fish and sold to reef aquarists. When the gobies died shortly after purchase, it was assumed that they were delicate or had very short lifespans. Neither assumption is true. Catalina Gobies are not tropical or sub-tropical fish. They are temperate, cold-water fish and quite hardy, if kept in the correct environment. The maximum temperature to plan for in a home Catalina Goby aquarium should be no more than 65 degrees Fahrenheit, maintained by a reliable chiller.

Some retailers are beginning to notice that their customers are educating themselves about the habitats of the species they are keeping. These retailers have changed their recommendations for Catalina Gobies and other cold water livestock, admitting that they are truly temperate. But some are still recommending the incorrect maximum temperature of 74 or 72 degrees Fahrenheit, which are still tropical temperatures. It’s a step in the right direction, but this temperature recommendation is still way too high.

According to, the maximum water temperature Catalina Gobies can be found living in is 71 degrees. This is during the hottest point in summer in shallow water. Keep in mind that our reef fishes can be found in waters where the temperatures reach more than 90 degrees during the summer. Even the least responsible aquarist would never attempt to keep reef fish at those temperatures. Our aquariums and captive reefs are very different from our pets’ natural habitats. Oxygen levels decrease at warmer temperatures, metabolism and respiration increase, and diseases/parasites can reproduce unchecked by inadequate dilution and overstocking (compared to the ocean). Attempting to keep any fish at the very top of its natural temperature range is going to shorten its lifespan and weaken the immune system. 71 degrees happens to be the top of a Catalina Goby’s temperature range.

Public aquariums have known for years that Catalina Gobies must be kept at low temperatures. The Monterey Bay Aquarium houses Catalina Gobies in a chilled aquarium maintained between 58 and 60 degrees. Their Catalina Gobies’ average lifespan is 2 years and they have no problems with disease. The Steinhart Aquarium in San Francisco keeps their Catalina Gobies at 60 degrees.

There are a few more species in the Lythrypnus genus, but only two show up in the aquarium trade with any regularity. The other is the Zebra Catalina Goby, Lythrypnus zebra. This species is not often collected, and the few that make it into the aquarium trade sell quickly. Not much is known about it except that its care is similar to the Catalina Goby’s.

There have been reports of Zebra Catalina Gobies being truly tropical because it ranges as far south as Clarion Island in the Revillagigedo Islands. The same argument could be made for its preference for cold water, as it ranges as far north as the cold waters of Caramel Bay, Central California. In fact, Zebra Catalina Gobies share most of their range with Catalina Gobies; the two species are often found living in the same area. lists L. zebra as sub-tropical, and L. dalli as temperate. It may be true that Zebra Catalina Gobies may tolerate slightly warmer temperatures than their cousin L. dalli, regardless, they should not be subjected to tropical temperatures in captivity.

I received this adult Lythrypnus zebra as a gift in September 2008. My aquarium temperature is maintained between 67 and 69 degrees in fall, winter, and spring. During the hottest summer months, I use a chiller to keep the temperature below 72 degrees. My Zebra Catalina Goby’s color began to fade as the aquarium temperature reached 72 degrees last summer. I turned the temperature down to 70 and it survived until the end of December 2009 when my aquarium “crashed.” Based on my experience with the handful of L. zebra I’ve worked with, I would consider L. zebra to be more delicate than L. dalli.

There are tropical gobies that rival the Catalina Gobies’ beauty and make much better additions to a reef aquarium. Gobies of the genera Trimma and Eviota are similar in size, color, and behavior. Trimma and Eviota gobies can even be kept in small groups with less aggression than groups of Catalina Gobies.

Responsibility begins with the collectors, wholesalers, and retailers, but we as hobbyists have a voice every time we purchase a specimen for our aquarium. We can educate fellow hobbyists about cold water livestock and avoid the temptation to keep them in our tropical aquariums only to enjoy them for a short time. By avoiding difficult to keep species, we can decrease demand for these animals, and fewer of them will be collected. We all play an active role in the future of our aquarium hobby.

Photos and article by Felicia McCaulley

Felicia has been keeping aquariums since the early 90s and has a keen interest in taxonomy, aquaculture, and seahorses. she is the former Liveaquaria Diver's Den photographer and now works for Philadelphia area's largest aquarium specialty store The Hidden Reef.

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