Choosing an Aquarium Substrate for your Tank

As a supplier of Atlantic marine specimens, we often get asked by customers how to go about starting up a new cold water aquarium. Like any building project, work begins at the bottom for most folks. Think tank, substrate, water, and organisms. 

Luckily over the years we have helped many high schools, universities, labs, and small aquariums get tanks up and running and so we have helped establish and troubleshoot hundreds of tanks from the tiniest day-care center touch-tank to large commercial aquariums across the country. This is not rocket-science for sure.

Choosing a substrate

Customers often ask us how to choose a substrate for their new cold water aquarium. For me, it just comes down to personal preference mixed in with some knowledge of the kinds of organisms one hopes to populate the tank with once running.

cobbly seabed

At GOM, we offer several products to put down on the bottom of a tank and customers often will order a mix of materials. Our "Cobbly Seabed" is the most popular. With a mix of small and larger beach-washed stones, it offers a mixed habitat that works well for crustaceans, worms, fish, and some molluscs. Fractured shale with its dark color makes a nice dark contrast to bring out the color of anemones, sponges, and tunicates but since it settles onto the bottom so densely it does not offer as many interstitial nooks and crannies as the cobble. The color of the shale is often mixed in with tiny bits of colorful white and blue clam and mussel shells that also provide a nice bit of color.

accounting for burrowing organisms

For customers who are wanting to have burrowing type animals such as annelid worms, clams, sea cucumbers, and some anemones like the northern cerianthids - a salt/sand mud is ideal. It takes a bit longer for the sediment to settle and the tank water to clear, but then it's ideal for these type organisms. It's a joy to see the sea life happily burrowed into their new homes with siphons out and tentacles waving back and forth in the current. Sometimes a fine sand also will work well for burrowing specimens. We have had clients split their tank 50:50 with cobble and sand providing a nice area for a bed of sand dollars as well as other organisms.

Collect it yourself

For those wanting to collect their own tank substrate DIY style, a trip to any local beach with a strong bucket will yield a variety of options. It is best to bring smaller pails as this stuff is HEAVY. Take a walk around the beach area first to scout out options for substrates before you start gathering up what you think you'd like to take home. Though it does seem like you will need to scoop up lots of material this is not always the case. We like to put a good solid 2-3" of material in the bottom of our aquaria, but even in a 50-gallon setup - this is not really much more than a solid 5-gallon pail. 3 smaller pails each filled a third will take care of your needs.

Preparing your DIY substrate

Back at home with your beach sand or rocks, you will want to rinse out any organic debris that is mixed in with the material. This is easy to do with a garden hose. Place small amounts into a small dishwashing tub or pail, put the garden hose into the bottom of the container and turn on the water. As the container fills, mix it around with your free hand and you will see bits of grass, bark, leaves, shells, mud, and other fine particles come up into suspension. If mixed continuously, this crud will flow up and out of the pail, leaving the good rocks and sand below. Continue until you feel that your substrate is sufficiently clean and then repeat with the next lot(s) until finished.  Soon you will have a nice supply of cleaned beach bottom to place in your tank as needed!

Get creative

Filling your aquarium with a substrate is totally up to your own artistic style.  Mix in large and smaller stones, sand, cobble, silt and create the look that you want.  Once you are satisfied it's now time to fill with seawater!

Thanks for reading,

Tidepool Tim

How to: Dig Spaghetti Worms

Spaghetti Worm

U-shaped burrow and castings. The hole ('volcano') is where the mouth of the worm is. The castings pile is the other end of the worm! The middle of the worm is deepest underground, at the center of the U's curve.

Spaghetti worms (Amphitrite spp.) live in super slimy tube burrows. They have a U-shaped burrow with the mouth at one end and their anus at the other end. The appearance of the front end of the worm gives it its name. Looking at the head you will see a bunch of red and tan colored tentacles stretching out of its burrow. The reddish tentacles are used for respiration. The whitish or tan tentacles are used for feeding. 

The worm lives in a burrow for protection. Only the feeding tentacles come up above the bottom. They stretch out in a radius around the burrow and they pick up food particles, plankton, detritus - this is all reeled back into the mouth as a food source. Imagine a worm that is named for the red (tomato sauce) and the tan (pasta) tentacles.

Locating the worm

We find these worms on the mudflat by looking for their piles of poop (castings) that lie in a pile at the end of the U-shaped tube burrow. Another interesting thing about these worms is that they sometimes share their tube with 12-scaled worms. Now, scaled worms are typically found on rocky bottoms in the depressions under the stones. What the advantage is to be tucked down in a tight little tube with a spaghetti worm is beyond me.....it has to be for feeding or protection I would guess. If anyone would like a very interesting research project - this is wide open!

Care

The spaghetti worm is a very versatile lab specimen. You can keep them in a small tub of salt water without any aeration, in a fridge for weeks. Some of our customers use these as a food source for anemones and fish.

Spaghetti worms (Amphitrite spp.).

The front end of the worm toward the bottom of the photograph is tentacled.

Welcoming Summer

This morning I kind of overslept and missed the low tide. I had come down to collect some Porphyra - which is a very thin papery type seaweed like sea lettuce. This type of seaweed seems to have several forms - maybe subspecies. Some grow at the mid-tide line and are attached to small rocks in a sandy/gravelly area. Another type is found only in areas of high current, this one is much darker and tougher and is towards the low tidal part of the beach. I did have to wade out to collect a few samples for a customer - so I considered myself lucky that didn't miss the 'boat' altogether. Had hoped to pick a few kelp plants as well but as you know you have to be at the low tide to find any of those...

A few days ago the remnants of a hurricane-driven storm came through our county with lots of rain and wind. When I reached the beach this morning it was not surprising to see a large beach-side windrow of 'storm-cast' rockweed stretching along the cobbly shore. It was a mixture of Fucus or bladderwrack and another type, Ascophyllum or knotted wrack. It was interesting to dissect out the windrow a bit and see just how Mother Nature had delivered this resource to its beachside location as well as what was found living inside. Initially, I suspected that the winds must have torn the plants from their holdfasts (the structure that attaches them to the rocks) but no - it was quite different.

What seems to have happened is that the storm's power actually loosened up the small stones upon which fairly large clumps of rockweed were attached. Rockweed is a name we use for a group of brown seaweed species found in the intertidal in great abundance. These stones of orange and grapefruit size are often buried in the beach substrate and provide a good solid place of attachment for rockweed plants. Once the wind and the waves hit them it is apparent that their foothold on the beach gave way and they became mobile. Because of the floats on the rockweed, that is their air bladders, provided enough floatation for the rocks to then be carried up the beach and into the tangle of other 'storm-cast' seaweed at the high tide line.  See my YouTube video about this seaweed and what happened to it in this storm. Besides rockweed there were bits of Spartina grass, little beach fleas, and other organisms found inside.

Pile of sea cucumbers.

I have to share this picture of some sea cucumbers we have here at Gulf of Maine. What a fantastic pile of sea pickles. I just dove my arms into the mass to see what they would feel like...it was creepy. Sea cucumbers don't respond much to touch other than to purse up their tentacles and wait for danger to go away. These guys came from a fisherman in Milbridge, Maine. Ug!

Tidepool Tim

How to: Collect Dwarf Brittlestars

Wow - pouring rain here in Maine today!  Nice to be inside, but I need to go dig some sandworms - guess I will be getting wet.

I want to share my collecting notes from yesterday when I found dwarf brittlestars, genus Axiognathus, in a local tidepool. It took me years of chancing upon these little echinoderms before I realized that they were not just small daisy brittlestars, genus Ophiopholus, but a new species to me. I needed to find a few dozens of these critters for a Gulf of Maine, Inc. customer, and with my experience, I knew right where to find them.

The key habitat for Dwarf Brittlestars seems to be in shell mounds. We find them hidden among cast blue mussel shells. They are a bit hard to spot at first, and they are not kidding when they call them "BRITTLE" stars. Not only are they tiny, one has to handle them with kid gloves so to say. The best way to pick them up it to not directly pick them up. We scrape them onto shell pieces so that when they end up in our buckets, they go substrate and all.

So I headed to the tidepool on a sunny morning and managed to hit the tide at just the right time. Dwarf Brittlestars prefer to be subtidal, but you can find them at the lower end of low tides in your area. I believe that like any tidal specimen as long as they can stay moist and protected during the drain off of the sea they will survive until the flood tide comes again.

Collection

Brittle star.

I use my hands like a small dredge in low wet areas to scoop up handfuls of shells and debris and then I spread this out on a flat surface like a rock or on a ledge. Then by carefully sifting through each shell I can look for their fuzzy little arms (rays) to tip me off to where they are hiding. Often you will see only one ray protruding from the shells, but with experience they become easier to spot.  I am not sure, but I think these guys feed on detritus. Whenever I get a big order of these for Gulf of Maine, Inc. I try and find a submerged mound of shells that seems well silted and muddy. The muddier the shell mound the better the habitat. Once I found a one gallon plastic milk jug that had been sitting on the sea floor for a long time. When we emptied it of muddy silt, out came a pile of dwarf brittles. It makes sense that this habitat would work well for them not only for feeding, but for protection.

Dwarf brittle stars.

It did not take me long to get the stars I needed to fill my order and to head off to work. I saw lots of sylky sea cucumbers, limpets, scuds, trumpet worms, and other inverts as I collected but did not need any of those at this time. Will get those later - it was time to head out. Lots to do as I have been away from the office for about three weeks and it is time to catch up.  

Catch me next time in the tidepools!

Tidepool Tim

Fisherman's Bucket

Hermits, hermits, hermits!  

Yesterday a local fisherman, Mike brought us in a pile of goodies fresh off his sea urchin drag boat. The weather had finally warmed up and the seas subsided enough for him to go out safely and try to make his living.

Besides the sea stars he brought in, I had asked him to keep an eye out for some hermit crabs and other small invertebrates. The hermits were HUGE - mostly flat - clawed variety, but there were some hairy hermits as well. Some of them were a bit stressed due to the anoxic conditions in the small pail and they had exited their shells. This was a bit concerning, at first - I wondered how they would do outside their shells. I placed them into my tank 'naked' for the evening and when I returned in the morning, they had all found suitable shells to move back into... 'shall I slip into something a bit more comfortable...?'.

The catch 

To my surprise, many of the hermits were egg-laden (gravid, berried?). You wouldn't be able to see this unless they had come out of their shells. The eggs look just like a lobster's egg mass.  The color was very black and the eggs a bit smaller though.

Hermit crab party.

Hairy hermit crab in my hand.

Hairy hermit crab with eggs (berried).

Flat clawed hermits.

Hermit crabs are one of the easier marine invertebrates to take care of in a tank. I feed mine bits of clam or squid when I have it. They will all gather around a lump of feed like cows at a trough, snipping and tearing bits to feed into their mouths. It is pretty neat to watch. As for the shell species that were represented - there were all the major mollusc snails we have here in Cobscook Bay. Waved whelk shells, moon snail shells, Stimpson's Coleus shells, and dogwinkle shells.  The moon snail shells are the most impressive. Since these snails get very large, the Hermits that inhabit them are big too.  

Sea grapes.

Sea peaches.

Toad crab.

Sea vase.

As for other species that came up in the fisherman's trawl, we found tunicates, other crabs, and worms.  There were several toad crabs, Hyas genus. The largest of these was about 8" across. The sea squirts in the pail were Sea Grapes (Molgula), Sea Vase (Ciona), Sea Potatoes (Boltenia), and Sea Peaches (Halocynthia). All of these were cemented to other tunicates in clusters or they attach to mussels, rocks, and other debris. Final inspection of the pail's contents revealed some fan worms, finger sponge, scaleworms and some tiny isopods - benthic creatures that had come up in the holdfasts of the tunicates and sponge. I dumped the remainder in our tanks. Hopefully, they will adapt to the smaller quarters and find their niche - it's a crab eat, worm eat, snail world in there!

Tidepool Tim