What is that!! A R2R guide to common new tank hitchhikers.

[Crabs McJones]

I found these strange inverts on my rockwork, it’s not like they’re NPS as they seem to really try stretch up to the light, any ideas? I thought either young Yellow Star Polyps or possibly a Tunicate (The only coral that was near them was a few months ago, these appeared a while after I moved the GSP though, also look too dull to be GSP).

Colonial hydroids I'm pretty sure.

 

[ArachnoJoozt]

What kind on snail is this. At night they come out by the dozens and hide during the day.
If I drop some food in at night, they are on it out of nowhere in 60 seconds.

Good-bad? Is it a Pyramidellidae? I was thinking about getting a clam. Is this snail a clam killer?

Look up Nassarius snails

 

[Firepony]

One of the greatest things about starting a reef tank is getting your live rock in and admiring all the diversity within it. The rock comes to life different creatures. This is a guide that I, along with a very well known critter identifier @KJ , have put together for the new reefer on what these hitchhikers are and whether they're a keeper or to pull them out.

Bristleworm -

Very common good hitchhiker. The jury is out on whether they're beneficial or not. Most consider them a vital part of your clean up crew. The hide within your live rock, coming out to pick up scraps of food and other detritus. Their numbers can become overwhelming based off how much food is available in the tank. If you overfeed, and they have access to an abundance of food, their numbers will increase dramatically. Be careful not to touch as the bristles on the sides of their bodies can be very irritating and cause an allergic reaction in some.


Fireworm -

Bad hitchhiker. Similar to the bristle worm, however if stung by the bristles on this little guy, its 10 times worse. DO NOT TOUCH UNDER ANY CIRCUMSTANCES! If found it is best to remove with a trap.

Pineapple Sponges -

Very common good hitchhiker. These little guys are a type of sponge. They are most commonly found in overflows and in high flow areas of the sump. However, they can sometimes bee seen in shaded areas of your rockwork.

Asterina Starfish -

Another common neutral hitchhiker. Jury is out on these guys as to good or bad. Some people love them, some hate them. They've been rumored to munch on coralline algae. They are also known to multiply very rapidly. Manual removal when seen is best to control their numbers.


Aiptasia -

Bad hitchhiker. This is a type of anemone that multiplies very quickly, and stings and kills anything that gets near it. Depended on how many you have, they're best removed by manually scraping them off the rock, and then using epoxy/superglue/kalk paste over where they were to prevent them coming back. A few predators that you can get for them include the peppermint shrimp, berghia nudibranch, and with a large enough tank, copperband butterflyfish.

Majano -

Bad Hitchhiker. This is another pest anemone that multiplies quickly and stings anything near it. Best removed by manual scraping off and super glue/epoxy/kalk past over its spot. Peppermint shrimp will reportedly consume them as well.

Vermedit Snail -

Very common neutral hitchhiker. They are generally harmless, but can multiply quickly based off nutrients in the tank, and can irritate corals. Manual removal or starving them out by putting a dab of superglue on the end of the tube is best to keep their numbers in check, as well as nutrient control.

Spirorbid Worm -

Very common neutral hitchhiker. These guys are most commonly found in overflows, and high flow areas of your sump. Can multiply very quickly and have been rumored to disrupt equipment such as pumps. Nutrient control keeps their numbers in check.

Ball Anemone -

Common neutral hitchhiker. They are found in shaded areas of live rock, and tend to not bother anything and numbers are kept in check with nutrient control. Are removed by the same means as the aiptasia and majano.

Stomatella Snail -

Very good hitchhiker. These guys are a great clean up crew member. They can be very elusive and most commonly found after lights out and are very fast moving. They feed off different algae in the tank.


Copepod/Isopod/Amphipod -

Very good hitchhikers. Often referred to as simply "pods" These little guys live within your rock work and make great food for your fish and corals. They can be the primary diet of certain mandarins.

Spaghetti Worm -

Good hitchhiker. Commonly found in the sand bed or live rock. They extend out multiple tentacles to catch floating detritus. Good member of your clean up crew.

Hydroids -

Bad hitchhikers. Good news is that they don't tend to live very long and die off on their own as the tank progresses.


Digitate Hydroids

Bad hitchiker- irritates nearby corals


Sponges -

Good hitchhiker. Very common filter feeders. Found in shaded areas of live rock

Serpent And Brittle Starfish -

Good hitchhikers. Are most commonly found by the arms extending out from cracks and holes in rock work. Feed off leftover food and detritus in the tank.

Bobbit Worm -

Very bad hitchhiker. These guys can grow to be very large and can kill fish. Most common means of removal is to remove the entire rock where the worm is housed. Be careful of the pincer teeth at the head of the worm.

Tunicate -

Good hitchhiker. Harmless filter feeder. At first glance looks like a sponge, except it pulses as it takes in and expels water, and reacts to touching it.

Limpet -

Good hitchhiker. Consumes algae. Don't seem to bother anything.

Fleshy Limpet

Neutral hitchiker. Algae grazer, but have been rumored to bother corals.

Slipper Limpet - Neutral hitchiker. Commonly attached to other snail shells. Don't cause any harm to the Snail or other tank inhabitants


Elephant Slug

Good hitchhiker. Algae grazer.

Chiton -

Good hitchhiker. Consumes algae. Does not appear to bother anything.

Peanut Worm -

Good hitchhiker. Lives in live rock and feeds off of extra food and detritus.

Gorilla Crab -

Bad hitchhiker. Can be found in live rock cracks, caves and holes. They are predatory and will hunt your shrimp and inverts. They can also grow rather large.

Benthic Ctenophores -

Been seeing this one pop up more and more lately, so I figured why not add them to the list.
They are a neutral hitchhiker. They mainly filter feed on zooplankton and small particulates in the water. Most commonly referred to as comb jellys.

Red Planaria Flatworm -

Bad Hitchiker. While they don't consume any coral, they can grow in numbers to the point where they smother coral. Caution should be taken as when these die off they release toxins that can wipe out a tank quickly.

Ghost Flatworm -

Neutral hitchiker. Doesn't harm anything. But does consume pods

Acoel Flatworm -

Neutral Hitchiker. Doesn't harm anything, however can grow greatly in numbers quickly

Polyclad Flatworm -

Bad Hitchhiker. Predatory towards clams and coral depended on subspecies.

Pumpkin Flatworm (Waminoa Sp)

Bad Hitchiker. Predatory. Can smother and kill LPS corals.

Acropora Eating Flatworm -

Bad Hitchiker. See name


I did not cover Nudibranch or snails in this thread as there are far to many variations to cover. If you have an unknown, please create a thread or post it in this thread and we'll try our best to ID it for you. If you have any additions to the list please PM me and I'll review it and add to the list.

Thank you so much!! I needed this list

 

[miham]

Hi. Does anybody knows, what is this?
Thanks.

 

[keithIHS]

ID please? It's about 1/4" in diameter and it can retract its tentacles.

 

[Crabs McJones]

ID please? It's about 1/4" in diameter and it can retract its tentacles.

Some sort of anemone. Doesn't appear to be aiptasia. Not sure.

 

[i cant think]

Some sort of anemone. Doesn't appear to be aiptasia. Not sure.

+1 to this

 

[keithIHS]

Thanks for taking a look. The base looks solid, but that's probably just due to the dark color. Looks like a limpet with tentacles. It had retracted its tentacles earler, so I turned out the lights and out came the tentacles. I had aiptasia in a QT tank last year, and from the many pictures I've seen, the base (stalk? foot?) of aiptasia looks skinny and clear, and aiptasia tentacles are longer; very different from this critter.
Here's a maybe better pic. The first pic is the underside of the foot, through the glass. The 2nd is maybe a little more clear than my previous post. BTW, there might be a 2nd, smaller one to the right in the 1st pic and above in the 2nd pic. The brown is probably dinos.
When in doubt, take it out?

 

[i cant think]

Thanks for taking a look. The base looks solid, but that's probably just due to the dark color. Looks like a limpet with tentacles. It had retracted its tentacles earler, so I turned out the lights and out came the tentacles. I had aiptasia in a QT tank last year, and from the many pictures I've seen, the base (stalk? foot?) of aiptasia looks skinny and clear, and aiptasia tentacles are longer; very different from this critter.
Here's a maybe better pic. The first pic is the underside of the foot, through the glass. The 2nd is maybe a little more clear than my previous post. BTW, there might be a 2nd, smaller one to the right in the 1st pic and above in the 2nd pic. The brown is probably dinos.
When in doubt, take it out?

It could be a walking dendro, I personally wouldn’t take it out completely and would have a separate tank to hold him in till you find out what it is definitely.

 

[keithIHS]

Base is soft, not solid (I poked it). No sign of its partner worm and the disk isn't elongated or a figure 8. Tidal Gardens lists walking dendro at $55, so that would be cool if it is.

 

[keithIHS]

Check it out. It split. Cool. Or maybe not. I suppose if the rate of doubling is reasonable, I could keep them under control.

 

[Dserra89]

One of the greatest things about starting a reef tank is getting your live rock in and admiring all the diversity within it. The rock comes to life different creatures. This is a guide that I, along with a very well known critter identifier @KJ , have put together for the new reefer on what these hitchhikers are and whether they're a keeper or to pull them out.

Bristleworm -

Very common good hitchhiker. The jury is out on whether they're beneficial or not. Most consider them a vital part of your clean up crew. The hide within your live rock, coming out to pick up scraps of food and other detritus. Their numbers can become overwhelming based off how much food is available in the tank. If you overfeed, and they have access to an abundance of food, their numbers will increase dramatically. Be careful not to touch as the bristles on the sides of their bodies can be very irritating and cause an allergic reaction in some.


Fireworm -

Bad hitchhiker. Similar to the bristle worm, however if stung by the bristles on this little guy, its 10 times worse. DO NOT TOUCH UNDER ANY CIRCUMSTANCES! If found it is best to remove with a trap.

Pineapple Sponges -

Very common good hitchhiker. These little guys are a type of sponge. They are most commonly found in overflows and in high flow areas of the sump. However, they can sometimes bee seen in shaded areas of your rockwork.

Asterina Starfish -

Another common neutral hitchhiker. Jury is out on these guys as to good or bad. Some people love them, some hate them. They've been rumored to munch on coralline algae. They are also known to multiply very rapidly. Manual removal when seen is best to control their numbers.


Aiptasia -

Bad hitchhiker. This is a type of anemone that multiplies very quickly, and stings and kills anything that gets near it. Depended on how many you have, they're best removed by manually scraping them off the rock, and then using epoxy/superglue/kalk paste over where they were to prevent them coming back. A few predators that you can get for them include the peppermint shrimp, berghia nudibranch, and with a large enough tank, copperband butterflyfish.

Majano -

Bad Hitchhiker. This is another pest anemone that multiplies quickly and stings anything near it. Best removed by manual scraping off and super glue/epoxy/kalk past over its spot. Peppermint shrimp will reportedly consume them as well.

Vermedit Snail -

Very common neutral hitchhiker. They are generally harmless, but can multiply quickly based off nutrients in the tank, and can irritate corals. Manual removal or starving them out by putting a dab of superglue on the end of the tube is best to keep their numbers in check, as well as nutrient control.

Spirorbid Worm -

Very common neutral hitchhiker. These guys are most commonly found in overflows, and high flow areas of your sump. Can multiply very quickly and have been rumored to disrupt equipment such as pumps. Nutrient control keeps their numbers in check.

Ball Anemone -

Common neutral hitchhiker. They are found in shaded areas of live rock, and tend to not bother anything and numbers are kept in check with nutrient control. Are removed by the same means as the aiptasia and majano.

Stomatella Snail -

Very good hitchhiker. These guys are a great clean up crew member. They can be very elusive and most commonly found after lights out and are very fast moving. They feed off different algae in the tank.


Copepod/Isopod/Amphipod -

Very good hitchhikers. Often referred to as simply "pods" These little guys live within your rock work and make great food for your fish and corals. They can be the primary diet of certain mandarins.

Spaghetti Worm -

Good hitchhiker. Commonly found in the sand bed or live rock. They extend out multiple tentacles to catch floating detritus. Good member of your clean up crew.

Hydroids -

Bad hitchhikers. Good news is that they don't tend to live very long and die off on their own as the tank progresses.


Digitate Hydroids

Bad hitchiker- irritates nearby corals


Sponges -

Good hitchhiker. Very common filter feeders. Found in shaded areas of live rock

Serpent And Brittle Starfish -

Good hitchhikers. Are most commonly found by the arms extending out from cracks and holes in rock work. Feed off leftover food and detritus in the tank.

Bobbit Worm -

Very bad hitchhiker. These guys can grow to be very large and can kill fish. Most common means of removal is to remove the entire rock where the worm is housed. Be careful of the pincer teeth at the head of the worm.

Tunicate -

Good hitchhiker. Harmless filter feeder. At first glance looks like a sponge, except it pulses as it takes in and expels water, and reacts to touching it.

Limpet -

Good hitchhiker. Consumes algae. Don't seem to bother anything.

Fleshy Limpet

Neutral hitchiker. Algae grazer, but have been rumored to bother corals.

Slipper Limpet - Neutral hitchiker. Commonly attached to other snail shells. Don't cause any harm to the Snail or other tank inhabitants


Elephant Slug

Good hitchhiker. Algae grazer.

Chiton -

Good hitchhiker. Consumes algae. Does not appear to bother anything.

Peanut Worm -

Good hitchhiker. Lives in live rock and feeds off of extra food and detritus.

Gorilla Crab -

Bad hitchhiker. Can be found in live rock cracks, caves and holes. They are predatory and will hunt your shrimp and inverts. They can also grow rather large.

Benthic Ctenophores -

Been seeing this one pop up more and more lately, so I figured why not add them to the list.
They are a neutral hitchhiker. They mainly filter feed on zooplankton and small particulates in the water. Most commonly referred to as comb jellys.

Red Planaria Flatworm -

Bad Hitchiker. While they don't consume any coral, they can grow in numbers to the point where they smother coral. Caution should be taken as when these die off they release toxins that can wipe out a tank quickly.

Ghost Flatworm -

Neutral hitchiker. Doesn't harm anything. But does consume pods

Acoel Flatworm -

Neutral Hitchiker. Doesn't harm anything, however can grow greatly in numbers quickly

Polyclad Flatworm -

Bad Hitchhiker. Predatory towards clams and coral depended on subspecies.

Pumpkin Flatworm (Waminoa Sp)

Bad Hitchiker. Predatory. Can smother and kill LPS corals.

Acropora Eating Flatworm -

Bad Hitchiker. See name


I did not cover Nudibranch or snails in this thread as there are far to many variations to cover. If you have an unknown, please create a thread or post it in this thread and we'll try our best to ID it for you. If you have any additions to the list please PM me and I'll review it and add to the list.

This post is awesome. I found a polyclad flatworm nestled between a shroom covered rock about a year ago in my 150. Wish I had this post then.

 

[i cant think]

It would be interesting to see if anyone had a tank just for all the “Bad” hitchhikers like the Pumpkin Flatworms because they don’t look too bad actually.

 

[Matt Carden]

 

[Crabs McJones]

Fleshy limpet

 

[saulgoodmannnn]

I saw one of these during the daytime hiding in between my candy canes at the base where they split off to different heads. Got some footage of it, is this a harmless shrimp? Explosion of them recently after adding Algae Barn copepods and some other products and feeding Ocean Magik.

 

[i cant think]

I saw one of these during the daytime hiding in between my candy canes at the base where they split off to different heads. Got some footage of it, is this a harmless shrimp? Explosion of them recently after adding Algae Barn copepods and some other products and feeding Ocean Magik.

The video doesn’t work for me however it sounds like they’re just normal amphipods from that description.

 

[saulgoodmannnn]

The video doesn’t work for me however it sounds like they’re just normal amphipods from that description.

Maybe it’s still processing, I clicked insert. Still a noob here. Guess I shoulda just uploaded screenshots

 

[i cant think]

Definitely just Amphipods. I think they feed on Copepods or something to do with them. They’re totally harmless though! Excellent food for your fish to hunt if you have anything like Halichoeres or wetmorella wrasses or even a butterflyfish.

Maybe it’s still processing, I clicked insert. Still a noob here. Guess I shoulda just uploaded screenshots

 

[saulgoodmannnn]

Definitely just Amphipods. I think they feed on Copepods or something to do with them. They’re totally harmless though! Excellent food for your fish to hunt if you have anything like Halichoeres or wetmorella wrasses or even a butterflyfish.

Thank you! Currently running fallow due to Ich/Velvet so I’m sure they will get pretty big by the time I reintroduce any fish