Everyone loves a freebie, and one of the beautiful things about this hobby is that you never know what is going to appear in your tank, seemingly from no-where.

Hitchhikers come in on live rock, coral frags, live sand, pretty much any time you introduce something new into your tank, you have the chance of obtaining a helpful little critter.

Not all hitchhikers are good to have (see the Bad Guys post here>>>), but this is a post celebrating the ones we can rejoice in having within our aquariums. Take a look at our Top 5 marine/reef safe hitch-hikers, hopefully soon to be spotted in your tank!

5. The Feather-Duster Worm

Feather-Duster Worm
Feather-Duster Worm

These harmless filter-feeders are lovely to see in a mature tank. They don’t do particularly well in new tanks and require a good supply of phytoplankton to survive.

Some crabs and certain types of fish have been know to like the taste of them, and will eat them, giving them quite a high mortality rate.

Because they are hard to care for and often end up as fish food, they can’t go further up our list, but we love seeing them in our tanks. If you have them thriving in your tank, it’s a good indication of a healthy tank.

4. The Bristle-worm


A controversial choice for number 4, the bristle-worm. Some people love them, others hate them.

Regardless of your feelings towards them, they are undeniably good clean up crew. They eat detritus and left over fish food, they will also eat any inhabitants that have come to an untimely end.

They can become very large, which is what prevents them from moving further up this list.

Top tip, if you have one Bristle-worm, you are likely to have many more! Don’t over-feed and you should avoid a population boom. There are some predatory wrasses that will also help keep the population in check.

3. The Spaghetti Worm

spaghetti worm
spaghetti worm

Spaghetti worms are related to the common earth-worm. They have a segmented body that will remain buried or wedged in a crevice, while their long white tentacles stretch out, looking for their next meal.

Like the bristle-worm, these worms will spend their time eating detritus and left-over foods.

They are not an overly mobile worm and once they have found a spot within your aquarium they will likely live out their days in that one spot.

They are also pretty creepy, but cool, to look at!

2. Various Pods


Copepods, Isopods,
Arthropods, Mysis, Amphipods, known to many as ‘pods’ are all tiny critters that are often imported into your tank via live rock, sand & coral frags.

Pods are beneficial for your aquarium as many of your inhabitants (including fish, corals & inverts) will eat them providing a natural food source. They are also scavengers, so will help with the clean up process, as well as eating some pest algae.

Live food for your fish that cleans the tank before it’s eaten… what could be a better freebie?

1. Corals

Hitchhiker Mushroom
Hitchhiker Mushroom

Ok, so technically this isn’t really a hitchhiker, but it’s got to be the best freebie you can get in a marine aquarium.

I don’t care if it’s a mushroom, a bit of Xenia or GSP, if it’s free and grows in my tank I am one happy bunny!

I was luck enough to get a free mushroom on the back of a hermit crabs shell, I have loved watching it develop from a tiny blob into a mini mushroom.

Some reefer’s have been luck enough to end up with highly sought-after SPS or high end Zoa’s, but whatever coral you end up with, count yourself lucky, as not all aquarists should expect such a lovely surprise!


This website is expensive to run in both monetary value and time. If you like what you see, and find this site helpful, please consider donating towards the running costs of the site.