Re:Eating or not?

Dear Tammy:

It’s difficult to determine what’s going on with your Sunbursts but I would be happy to share my thoughts on the matter with you. As long as they are eliminating well-formed feces, regardless of color, that’s a pretty good indication that the seahorses are eating something, so if they haven’t been eating the frozen Mysis as usual lately, it’s safe to assume that they have been dining on the pod population in the aquarium, just as you suspect.

Seahorses that are eating Vibrance-enriched frozen Mysis usually produce dark-colored fecal pellets, which may range anywhere from brown to orangeish or even reddish in coloration. The colorful feces are due to excess carotenoids in the Vibrance that weren’t fully digested and broken down as they passed through the gastrointestinal tract. So we expect to see a change in coloration in the feces when the seahorses stop feeding on the Vibrance-enriched frozen Mysis. The whitish coloration of their feces may simply be a reflection of the fact that they have been grazing on natural fodder lately rather than ingesting a lot of carotenoids, as they do when they are eating the enriched Mysis.

So the whitish coloration of their feces isn’t necessarily a cause for concern as long as they are well formed. That’s probably just a reflection of the change in their diet, not an indication that they are malnourished. But if they begin producing white, stringy feces, that’s a pretty clear sign that they are not getting enough to eat.

It’s very possible that your seahorses are feeding on pods in the aquarium between meals, and that this accounts for their loss of appetite, especially if you have seen them actively hunting and searching through the new macroalgae for food. The diligent aquarist is always concerned about a change in the eating habits of his seahorses, but there is a fairly easy way to determine if they are still getting enough to eat despite declining the frozen Mysis recently. Just make sure all your Sunbursts have full bellies at the end of the day, as indicated by their well-rounded abdomens. After a good feeding, the seahorses belly rings should be flush or even slightly convex in cross section when viewed from head on. (We never want to see sunken, severely pinched-in abdomens on our seahorses! Concave belly rings are a sure sign of an underfed seahorse, with the sole exception of a female that has just transferred her eggs.)

So if you want to check whether your seahorses are eating well or not, Tammy, examine them head-on and check out their gut. Their abdomens or belly plates should bulge out slightly or at least be flush with their flanks, not pinched in or sunken. In other words, when viewed from the back or from head-on, the cross-section of their abdomens should appear concave "( )" or flush "l l" rather than concave ") (" or pinched in.

Another good way you can doublecheck to see if they are getting enough to eat on a daily basis is to examine their fecal pellets, Tammy, just as you have been doing. If the fecal pellets they are producing have not changed in quantity or appearance, you can be assured they are getting plenty to eat. But beware if they start producing white, stringy feces rather than their usual well-formed feces — those pale, stringy feces are often a sign of a seahorse that is underfed and not getting enough nourishment.

As long as your seahorses are actively searching the macroalgae for pods, you can use that to your advantage to help get them eating the frozen Mysis again regularly as well, Tammy. Seahorses love to perch on clumps of macroalgae and are naturally attracted to it as a convenient hitching post. Just release a baster full of frozen Mysis over the clumps of macroalgae, and you will find that the Mysis becomes trapped amongst the tightly packed branches of the algae, clinging to the cluster of fronds wherever it happens to settle. The hungry seahorses will then carefully scour the branches of the macroalgae for the Mysis just as if they were hunting live shrimp and pods amid the beds of seagrass in the wild. Macroalgae is ideal for use as a natural feeding station in this way because the seahorse’s tubular snout is adapted for suctorial feeding, perfectly designed for plucking small invertebrates from amongst dense foliage.

In the meantime, it’s a good idea to perform a series of partial water changes as a precaution. Some of the factors that are known to contribute to a loss of appetite in seahorses are poor water quality, depleted trace elements and minerals, low pH, and a drop in the levels of dissolved oxygen, and water changes can help correct all of the above.

Regardless of how your water chemistry appears right now, a good place to start addressing the situation whenever there is a suspected loss of appetite is to perform a 25%-35% water change immediately to safeguard the water quality and replenish depleted trace elements and minerals. (At first glance your aquarium parameters may look great, but there are some water quality issues that are difficult to detect with standard tests, such as a decrease in dissolved 02, transitory ammonia/nitrite spikes following a heavy feeding, pH drift, a deficiency and trace elements/minerals, or the gradual accumulation of detritus. A water change and cleanup, or a series of partial water changes, is a simple preventative measure that can help defuse those kinds of hidden factors before they become a problem and stress out your seahorses. These simple measures may restore your water quality as well as your seahorses’ appetite.)

Seahorses can normally adapt to a wide range of salinity, so I don’t think the gradual rise in the specific gravity of your aquarium would cause some of the seahorses to go off their feed. (A drop in the pH is another matter and low pH is often associated with the loss of appetite.) But I would gradually lower the specific gravity in your seahorse tank to the usual level just to make sure the rise in salinity is not stressing the seahorses.

Be sure to check your dissolved oxygen (O2) level in addition to the usual pH, ammonia, nitrite and nitrite readings.. A significant drop in O2 levels (6 – 7 ppm is optimal) or rise in CO2 levels is very stressful yet easily corrected by increasing surface agitation and circulation to promote better oxygenation and gas exchange. Add a shallow airstone just beneath the surface if necessary and increase the circulation throughout your tank it possible.

Whether the beneficial effects are due to improving water quality or replenishing depleted trace elements or something else altogether, performing a major water change as described above often sets things right when seahorses are off their feed for no apparent reason.

Best of luck with your Sunbursts, Tammy. My best guess as is that they are probably taking advantage of the abundance of pods that you recently added to the aquarium with the new macroalgae and zooplankton mix, and I’m thinking they will probably resume their normal feeding habits again once they have depleted the pod population sufficiently. But keep a close eye on them in the meantime for any other symptoms or indications that might suggest a more serious problem.

Respectfully,
Pete Giwojna