Reply To: Little white bugs crawling on seahorse

Pete Giwojna

Dear Anna:

I don’t think you need to worry about the small white bugs in your tank. I am thinking they are most likely some sort of copepod, which will appear naturally in an aquarium with live rock and live sand, and which are almost always considered to be desirable.

I don’t think they are parasites because most of the external parasites that plague marine fish are protozoans that are invisible to the naked eye. Some are visible during certain stages of their development, such as the encysted parasites that cause Cryptocaryon irritans (or marine ick, as it is also known). These cysts appear as white spots on the body of the fish that are about the size of a pinhead, and are the reason that marine ick is also sometimes known as white spot disease. But the white cysts only form on the bodies of the fish, and are therefore never seen in the aquarium water or clinging to the aquarium glass, so we can rule them out for sure.

The other ectoparasites that are visible to the naked eye don’t look anything like tiny white bugs, Anna. For instance, gill flukes and trematodes appear as either black spots on the fish or look like opaque sesame seeds, whereas nematodes look like tiny white worms. So the “small white bugs” you describe sound much more like copepods, which seahorse keepers want to populate their aquarium, since they are good seahorse food in the adult stages.

As I said, it is normal for copepods to appear in a marine aquarium that has live rock and live sand at some point, Anna. Indeed, the unexpected appearance of various crustaceans and microfauna in a SHOWLR tank is the very reason aquarists refer to these rocks as “live.” It can be very difficult to accurately identify all of the mysterious life forms that may blossom from your live rock over the months and years, but 99% of them are harmless, benign, or beneficial to the aquarium and the pageant of life that appears in microcosm from the LR is fascinating to observe 100% of the time.

There are really only about four types of undesirable hitchhikers that sometimes sneak into our tanks concealed amidst the live rock or upon live sponges or live corals and which are problematic for a seahorse tank, Anna, as outlined below:

(1) mantis shrimp;
(2) predatory crabs;
(3) fireworms and bristleworms;
(4) rock anemones.

With the exception of the four undesirable pests mentioned above, most anything else that emerges from your live rock or live sand will be benign or even beneficial for your aquarium, Anna, so you needn’t be too concerned about your tiny white bugs at this point.

Reef Central ( is the place to go to identify all of the interesting critters that pop up from live rock or live sand or natural seawater. They have an excellent series of photo galleries on their site, including one devoted to Reef Tank Hitchhikers, so you might check in there and see if any of their photos look like the super small white bugs you are concerned about:

Reef Central has a discussion forum devoted just to seahorses, so it’s a good place to visit from time to time anyway.

Also, if you copy and paste the following URL into the Web browser on your computer, it will take you to another site with lots of photographs of aquariums hitchhikers that may help you to identify your mysterious tiny white bugs:

Finally, Anna, if you go to and look in the photo galleries in the “Fauna” section, that’s another good way to identify the hitchhikers and mysterious invertebrates that appear seemingly out of nowhere in a dynamic marine aquarium:

Let me know if you find any photos that look like your small white bugs and can verify their identification, Anna (look closely at the photos of any copepods, in particular), and I will be happy to advise you whether they are harmless or should be removed from the aquarium.

But if the little white bugs become too numerous or seem to be irritating your seahorse more frequently, you can keep them under control by obtaining a mandarin goby or dragonet, as they are also known. These are small, extremely colorful and beautiful marine fish that love to eat copepods and small bugs, amphipods, etc., and which are completely peaceful and entirely compatible with seahorses. Captive bred and raised mandarins are available and can be purchased online from companies such as ORA (Oceans, Reefs, and Aquariums) or Biota.

Pete Giwojna, Ocean Rider Tech Support

America's Only Seahorse Aqua-Farm and One of Hawaii's Most Popular Attractions

Ocean Rider seahorse farm is a consistent Trip Advisor Certificate of Excellence Award Winner and "Top 10 Things To Do" Kona, Hawaii attraction. Our "Magical Seahorse Tours" are educational and fun for the whole family.

Tour tickets are available for Purchase On-Line. Space is limited and subject to availability.

small seahorse Ocean Rider, Inc. is an Organic Hawaiian-Based Seahorse Aqua-Farm & Aquarium that Follows Strict Good Farming Practices in Raising Seahorses and Other Aquatic Life.

Seahorse Hawaii Foundation

Inspiring ocean awareness by saving the endangered seahorse and sea dragons around the world from extinction through conservation, research, propagation, and education.

Help us save the seahorse and the coral reefs they live in with a tax deductible contribution to the Seahorse Hawaii Foundation. You will be helping to protect and propagate over 25 species of endangered seahorses, sea dragons and friends.

Make A Tax-Deductible Donation Today!

A Different Kind of Farm (Video) »

Ocean Rider Kona Hawaii

Ocean Rider Kona Hawaii
Seahorse Aqua-Farm & Tours

73-4388 Ilikai Place

Kailua Kona, Hawaii 96740

Map & Directions


Contact Ocean Rider

Copyright ©1999-2023
All Rights Reserved | Ocean Rider Inc.

My Online Order Details

Purchase Policy

Site Terms and Conditions