Zoa Eating Nudi (ZEN), just how small are they? What do they look like? Pictures for education.

[ZoaKiller]

Recently there was a possibly well meaning but grossly inaccurate statement made that Zoanthid Eating Nudibranch (ZEN) are "easy to see with the naked eye" and can simply be "manually removed".

While both might be true for near full "adult" ones it is absolutely false about younger or freshly hatched ones.

Seen below are two images of "adult" size ZEN which are visible to the naked eye if you know what you are looking for. (Photo credits to the original sources)

Though the brown coloration is the one most frequently seen there are reports of them coming in other colors. While it's debated if these other colors are due to uptake of coloration from eating a particular zoa morphs, a camouflage that the zoas can adapt to whatever they're trying to blend in to, or if the coloration is present from birth due to exclusive predation on one specific type of zoa (again photo credits to the original posters)

IMPORTANT NOTE: Photo credit for the second image down on this first post has been claimed by @LisaAP . I am working on getting a link to the original source vs the screen shot from Google images. And will add it when I get it.

 

[ZoaKiller]

What follows are semi-decent at best pictures I've taken from my own experiences with ZEN. The first photo is a coue of ZEN who survived a very concentrated treatment with Flatworm Exit (FWE), around 4.3 x the recommended dose.* These were not only exposed to the high dose FWE but had also been kept in a 2 oz floating frag cup for around 60 hours in the treated water without flow, without food, without circulation, without water exchange.

These specimens started out the more frequent brow/white coloration and have not faded to almost translucent likely due to lack of food, circulation, etc.

However they are both very much alive and crawling around. They were euthanized after these pics as I didn't have the time to deal with them.

 

[ZoaKiller]

Now some examples in situ (still in the tank/on colonies). My apologies for the washout coloration but I was in a hurry to get the photos so I could pull the colonies to treat them.

This picture shows four ZEN. See if you can spot them all.

The following two images are the same colony with a macro lense. Each picture shows one ZEN that is "easily visible". See if you can spot them.

Ok did you spot them all? Answer on the next reply.

 

[ZoaKiller]

Ok so here's your answers. I observed this colony with the naked eye, a magnifier, and a macro lense and even rotated it a bit for about 7-8 min total to count the ZEN and attempt to take pictures. Again these were brown and white but between tuning my LEDs and trying to figure out my exposure, ISO, WB and wanting to get the dang things out of my tank these are the pics I ended up with.

 

[ZoaKiller]

Ok so those were the "easy ones" it brings me to the crux of my point about them being "big enough to see with the naked eye" and can "just be eliminated" with "manual" removal.

The following image is a colony being attacked by freshly hatched ZEN. Yes I did in fact take this image with a potato I'm sorry. And yes these are just technically visible to the naked eye.

The following image has two confirmed ZEN. Can you spot them? Spoiler in next post.

 

[ZoaKiller]

The image was taken of a colony sitting a ways back from the glass. I assume, unfortunately, that I will get an opportunity to photograph more in the future and I will clean my glass and work on balancing my light and camera before taking pictures.

They may look like pods or simply detritus but if you observe for 8-10 min you will see a movement patter that is unique from any pod, worm, or snail.

If you are hoping to eliminate ZEN by manual removal and you have more than just a couple of very easily reachable and visible zoa colonies in your tank you are in for a bad time.

They were removed with great care using a scaple and confirmed with a magnifying glass. These examples are about one and a half to two days from hatch .

Yes I deliberately let the eggs hatch to 1. See how small babies would be. 2. To see if my 6 line wrasse (or any other occupants) would eat either the eggs or the babies. Obviously they didn't. 3. To test out various dips on. (More to come on that on a separate thread).

 

[Islandvib3s]

Have you tried the bayer dip? You'll have to take the zoas colonies out and do a few rinse baths after the bayer dip but I've heard that stuff works,but I havent personally ran into these guys yet. Hopefully this helps.

 

[chaostactics]

Have you tried the bayer dip? You'll have to take the zoas colonies out and do a few rinse baths after the bayer dip but I've heard that stuff works,but I havent personally ran into these guys yet. Hopefully this helps.

Bayer dip is what I was using when this happened but it was probably either from not circulating the water enough during the dip or failing to remove eggs. Dips have been covered by others and I will probably make a thread dedicated to dips all by themselves.