Please visit our Sponsors

Related FAQs: Fish and Invertebrate Marine Set-ups, FOWLR 2, FOWLR 3, FOWLR Set-Ups, FOWLR Set-Ups 2, FOWLR Lighting, FOWLR Filtration, FOWLR Skimmers, FOWLR Livestocking, FOWLR Livestocking 2, FOWLR Livestocking 3, FOWLR Livestocking 4, &FOWLR Maintenance, FOWLR Disease, LR Lighting, Reef Systems, Coldwater Systems, Small Systems, Large Systems, Marine System PlumbingBest Marine Set-Up FAQs 1, Best FAQs 2, Marine Set-Up 1, FAQs 2, FAQs 3, FAQs 4FAQs 5, FAQs 6, FAQs 7FAQs 8, FAQs 9, FAQs 10FAQs 11, FAQs 12FAQs 13FAQs 14FAQs 15, FAQs 16FAQs 17FAQs 18FAQs 20FAQs 21FAQs 22, Moving Aquarium SystemsBiotopic presentations

Related Articles: Fish and Invertebrate Systems, aka FI/OWLR Systems by Bob Fenner, Marine Planning, Getting Started with a Marine Tank By Adam Blundell, MS, Fish-Only Marine Set-up, Reef Systems, Coldwater Systems, Small Systems, Large Systems, Plumbing Marine SystemsRefugiumsMoving AquariumsMarine Biotope, Marine LandscapingFishwatcher's Guides

/The Conscientious Marine Aquarist

FOWLR Systems Plus

Live Rock, Fishes & Hardy Invertebrate Biotopes That Thrive Together

Robert Fenner



Sidebar: Portfolio of Rugged Invertebrates

            A brief preview of some invertebrate organism groups that are typically verboten in reef tanks:




Lobsters; smaller tropical species for mid-sized systems, and larger possibilities for those of hundreds of gallons. Shown, the Zapata, Slipper Lobster Scyllarides squamosus in Baja. There are also clawed and spiny lobsters of all sizes to consider; though each is to degree predaceous, given food directly, they generally leave tankmates alone.  


Saron Shrimps; There are several species, but I’ll only share the one commonly offered in the trade here: Saron marmoratus Olivier 1811), Marble or Saron Shrimp. Found throughout the tropical Indo-Pacific. Usually collected out of Hawai'i for the U.S., the Red Sea for European markets. Usually found in pairs in the wild. Will fight to the death if same sex individuals are placed together. Males with much longer first pair of walking/fighting legs.  Get along fine with fishes, other crustaceans. A male in Hawai'i at night.


Large Hermit Crabs; There are a few more than golf ball to fist sized hermits that will tear up reefs, but are suitable for larger rough and tumble fish and invertebrate systems. Here’s Dardanus megistos (Herbst 1789), Shell-Breaking Reef Hermit Crab, often sold as the White Spotted. Members of this genus are predaceous, and will gladly consume any fishes they can get their claws on. To six inches. P*lace with large, aware fishes only. 




Arrow Crabs; There’s more than one, but all we see in the trade is Stenorhynchus seticornis (Herbst 1788), the Caribbean Arrow Crab. Not to be trusted with small to medium fish tank-mates (may spear with rostrum, otherwise consume). Safe with hardy native corals and anemones, larger fishes. 




Sally Lightfoot Crabs; this common name includes a few species. At right is the one of the Sally’s: Grapsus grapsus. Percnon gibbesi, is another one; AKA as the Nimble Spray Crab. Tropical West Atlantic. Live in reefs, rocky areas. Hide under Urchins and rocks. Both need a platform to get up/out of the water.






Decorator Crabs; Here also there are several species of Decapods with the same appellation. I’ll show you an Ethusa species with a Cassiopeia on its back here, but there are others that sport sponges, hydroids, algae…


Bigger Gastropods; This encompasses a large number of organisms; particularly snails. Of the choices here, aquacultured Fighting Conchs are a fave. Shown Lobatus gigas (formerly Strombus gigas), the Queen Conch


Larger Urchins; Bigger urchins need bigger spaces to move and feed from; plus a dearth of benthic life that can be damaged by poking. Diadema paucispinum (A. Agassiz 1863), a Long-Spined Sea Urchin. Pacific; Hawai'i and islands of the South Pacific. To about twelve inches maximum diameter, with spines. Usually in 60 or more feet of water on a vertical surface. Common name means "few spines" which you may not agree with if you get poked but good. 



Larger Sea Cucumbers; Just beware of the ones that have the propensity for extruding their toxic Cuvierian Tubules as this one is doing here. Bohadschia argus Jager 1833, the Ocellated Sea Cucumber. Western Indian Ocean; Madagascar, Seychelles to Sri Lanka. Pacific Ocean; Malay Archipelago to South Pacific Islands. Needs large quarters than captivity allows. To two feet in length. 





Even a few noxious corals… that most folks avoid, at least in quantity. Colt/Klyxum, Cauliflower Coral, the many Clavulariid Polyps that are uber invasive. Shown: a fave for Red Sea biotopes, various Xeniids.



            Fish Only With Live Rock systems may seem like too-old school to full-blown reefers, but there are still places for marine systems that eschew the use of live hard and soft corals; as you’ll soon see, and here’s the twist; adding some hardy invertebrates they become FIWLR aquariums. Yes; there are numerous combinations of fishes, tough invertebrates and live rock system by gallonage that make powerful, beautiful displays.

            FOWLR tanks have been with us since the advent and popularization of live rock use; in the US, about the mid 1980’s. The purpose and use of live rock is multi-fold of course: Not only as a pre-eminent décor material that can be fashioned into caves, walls, bommies, nooks and crannies of all sorts, but for its functional aspects… promoting overall complete and stable ecology through aerobic and anaerobic bacterial culture, sponsoring algal et al. Protistan populations, and serving as structure for many groups of invertebrate life. Really; where would our hobby be without live rock? I almost shudder when I think back to the pre LR days of bleached corals, shells, barnacles… plastic plants… dolomite gravel! Oh yeah; not a pretty memory; and think of all the bleach stains on floors!

            Adding selected hardy invertebrates to FOWLRs without them becoming full-blown reef systems is simple to do, and makes for much more interesting displays. Herein are some of my ideas for great mixes of readily available fishes, hardy invertebrates and macroalgae in terms of natural setting and tank size.

On With the Model Biotopes by Volume!

Size: 40 Gallon Indo-Pacific Starter

Organisms:                                                                               Scientific Name:
1 White Tailed Dwarf Angel                                                   Centropyge flavicauda
3 Blue Chromis                                                                       Chromis viridis
1 Dwarf Hawkfish                                                                  Cirrhitichthys falco
Sea Lettuce                                                                            Ulva sp.
2, 3 Nerite Snails                                                                     Nerite sp.
1 Mithrax Crab                                                                       Mithraculus sculptus

Notes on Livestock:
A Fisher’s Dwarf Angel would be a good substitute for the White-Tailed if you can’t find it or prefer the Fisher’s looks.
The Blue Chromis is the most popular of Damsels, but any small, easier-going Pomacentrid will do.
The Sea Lettuce is best purchased aquacultured. You can find this online under the genus name.

Notes on Aquascaping:
Just some live rock, ten, twenty pounds, mounded up in a corner is what I suggest. This is enough LR to gain all the benefits, but not so much as to take up significant volume.


Size: 50 Gallon Cozumel Shallows

Organisms:                                                                               Scientific Name:
2, 3 Cherub Angels                                                                  Centropyge argi
1 Lantern Bass                                                                                     Serranus baldwini
1 Royal Gramma                                                                     Gramma loreto
2, 3 Cleaner Gobies                                                                 Gobiosoma sp.
1 Blue Sponge                                                                         Haliclona sp.  
1 Condy Anemone                                                                  Condylactis gigantea
1 Sea Grapes                                                                            Caulerpa racemosa

Notes on Livestock:
All other basses from the area, including other Serranus species, get too large. S. baldwini itself max.es out at 3”. There’s a large selection of Gobiosoma species in the tropical West Atlantic; take your time selecting these.
I realize this isn’t much fish life, but the paucity here in numbers and size is more than made up in peacefulness and interesting behavior.
Though I really like row pore sponges, Aplysina species, these aren’t offered in the trade; thus I’ve listed one sponge that is… DO keep your eyes open at your dealers if they stock LR from the trop. W. Atlantic… for hitchhiking sponges. Here’s hoping you can pick up a hardy/ier photosynthetic species for cheap. If you can’t locate this Caulerpa species, no worries; as there are several others that are found in Cozumel

Notes on Aquascaping:
Best here is a loose stacked sloping left or right wall of largish pieces of live rock; granting plenty of nooks and holes for these fishes to dart in and out of. Do make a prominent ledge to set your Condylactis anemone and sponge. This Caulerpa algae grows on rock, others on sand substrate.


Size: 75 Gallon Bonaire Blowout!

Organisms:                                                                               Scientific Name:
1, 2 Flameback Angels                                                            Centropyge aurantonotus
1, 2 Yellowheaded Jawfish                                                      Opistognathus aurifrons
1 Blue Hamlet                                                                         Hypoplectrus gemma
1 Harlequin Bass                                                                     Serranus tigrinus
1, 2 Black Cap Basslets                                                           Gramma melacara
1 Sea Plume                                                                            Pseudopterygorgia sp.
1 Azure Vase Sponge                                                              Callyspongia plicifera
Halimeda Algae                                                                       Halimeda copiosa or other

Notes on Livestock:
The Flameback Angel is found lower in the tropical West Atlantic, all the way to Brazil; where great specimens can be had. I would limit the number of Jawfish here to allow a good two square feet of space per specimen; DO provide a mix of fine sand and rubble for their burrowing activity. Any species of Hamlet would go here, but I really like the blue for its color.
Other small basses can be subbed here of course.
The Sea Fan and Sponge should be purchased with a bit of live rock attached, and this anchored into your established LR arrangement. Halimeda species algae should be tucked onto rock where there is good light; it will attach itself in time .

Notes on Aquascaping:
Rock arranged in a pile to one side, going about half way up the tank side, a bommie of stacked rock on the other end, with a sandy patch between would be my choice here; giving the fish defined areas to duck into as well as space to cross over.


Size: 90 Gallon Western Pacific Mix

Organisms:                                                                               Scientific Name:
1 Coral Beauty Angel                                                              Centropyge bispinosus
2 Fire Gobies                                                                           Nemateleotris magnifica
5 Blue Devil/Damsels                                                              Chrysiptera cyanea
3 Yellowfin Fairy Wrasses (1 M, 2 F)                                      Cirrhilabrus flavodorsalis
2 Cleaner Shrimp                                                                     Lysmata amboinensis
1 Fromia Seastar                                                                      e.g. Fromia elegans
Brown Dichotomous Algae                                                      Dictyota species

Notes on Livestock:
Another western Pacific Ocean Centropyge could supplant the Coral Beauty. The Oriole, or Bicolor is one such alternate choice. Place the dartfish gobies last, as they appreciate more established systems. The Damsels can go in anytime; perhaps first as “test fish” to ascertain the system’s readiness for stocking.
Other species of cleaner shrimp, Fromia star can be substituted of course. Look at fresh live rock imports at your dealer for common hitchhiking Dictyota.

Notes on Aquascaping:
A/the “standard” wall of rock applies here, perhaps with a dip towards the middle area, and not quite so high on the right. For most humans, a higher point of impression is taken on the left, with the view sliding to the right.


Size: 100 Gallon Polynesian Paradise

Organisms:                                                                               Scientific Name:
1 Flame Angel                                                                       Centropyge loricula
1 Golden Wrasse                                                                   Halichoeres chrysus
1 Pacific Saddleback Butterflyfish                                          Chaetodon ulietensis
1, 2 Scott’s Wrasse (1 M)                                                      Cirrhilabrus scottorum
3, 4 Canary Demoiselle                                                          Chrysiptera galba
1 Tiger Cowry                                                                       Cypraea tigris
1, 2 Maxima Clams                                                                Tridacna maxima
1, 2 Hatpin Urchins                                                                Diadema setosum
1 Linckia Seastar                                                                   best Linckia multifora

Notes on Livestock:
I’ve shown a Flame Angel photographed down in Nuka Hiva in the Marquesas, but one from throughout its wide range will do. Best to introduce the Centropyge angel first, so it becomes well established without any competition for food and space. If a Tiger Cowry is too big for your tastes, there are other cypraeids to choose amongst. The small species of urchin mentioned is a frequent hitchhiker on S. Pacific live rock imports.

Notes on Aquascaping:
One peaked wall in the left corner (unless there was some compelling outside of the system reason to situate it on the right) of rock is my choice for this size, shape tank, and the fishes listed. Enough hiding spaces afforded for psychological comfort, leaving the majority of room for open space cruising.



Size: 150 Gallon Fiji Reef Bottom

Organisms:                                                                               Scientific Name:
1 Koran Angelfish                                                                  Pomacanthus semicirculatus
1 Banana Wrasse                                                                   Halichoeres hortulanus
7 Blue Chromis                                                                      Chromis viridis
5 3-Stripe Dascyllus                                                               Dascyllus aruanus
1 Blue Tang                                                                           Paracanthurus hepatus
1 Dwarf Hawkfish                                                                 Cirrhitichthys falco
1 Fiji Blenny                                                                           Ecsenius fijiensis
Galaxaura Red Algae                                                             Galaxaura species
1, 2 Aquacultured Bubble Tip Anemones                                 Entacmaea quadricolor
1, 2 Fluted Giant Clam                                                            Tridacna squamosa
1, 2 Banded Coral Shrimp                                                       Stenopus hispidus

Notes on Livestock:
The Koran is one of most favorite angelfishes; and doesn’t get too large for this size/shape tank. Just the same, if you prefer, there are some larger Centropyge in Fiji that you could swap out for; or a pair/trio of the Swallowtail Angel, Genicanthus melanospilos. The Banana Wrasse does get large, but it’s a peaceful, non-destructive species. The Damsel groupings are for show and motion all day, and the Blue/Palatte/Pacific Yellowtail Tang for color and interest: along with the little Blenny and Hawkfish.
You might well get lucky finding useful macroalgae growing on good quality live rock, otherwise, look for this and Tridacnids as aquacultured products.

Notes on Aquascaping:
Here I would amass a centrally placed stack of rock, with some overhangs, but mostly for the fish to swim around; to provide habitat and blocking each other visually to reduce aggression and stress.


Size: 180 Gallon Hawaiian Drop Off

Organisms:                                                                               Scientific Name:
1 Bandit Angelfish                                                                   Apolemichthys arcuatus
2 Pebbled Butterflyfish                                                            Chaetodon multicinctus
1 Coris Wrasse                                                                       Coris gaimard
1 Christmas Wrasse                                                                Halichoeres ornatissimus
2, 3 Jordan’s Wrasses (1 M)                                                    Cirrhilabrus jordani
Ogo (Tang Heaven/IPSF)                                                        Gracilaria parvispora 
Collector Urchin                                                                      Tripneustes gratilla
Black Cucumber                                                                     Holothuria atra
Hawaiian Red Reef Lobster                                                    Enoplometopus occidentalis

Notes on Livestock:
Yeah, I know Bandit Angels are expensive; but if you can afford to procure an aquacultured specimen, I can’t encourage you enough. IF too dear, a Potter’s (maybe with the Macropharyngodon wrasse Batesian mimic!) or even a Hawaiian Flame Angel will do. Or, if you hit the lottery, look for a pair of Masked Angels, Genicanthus personatus. These have also been cultured, but wild or not… muy expensive.
Similarly, there are a few dozen other Labrid possibilities that hail from the 50th State.
There are several species of Gracilaria in Hawaiian waters, the one mentioned is a favorite food of some marine fishes, but is otherwise ornamental. It can be purchased over the Net from Indo-Pacific Sea Farm.

Notes on Aquascaping:
Three separated stacks of rock (larger, flatter pieces on the bottom of the tank first), ala three bommies is how I’d place the LR here in a six foot long system; the bommie in the middle perhaps a bit shorter and broader.


Size: 240 Gallon Hawaiian Shore Biotope!

Organisms:                                                                               Scientific Name:
1, 2, 3 Potter’s Angelfish                                                         Centropyge potteri
1 Naso Tang                                                                           Naso lituratus
1 Shortnose Wrasse                                                                Macropharyngodon geoffroy
3 Pyramid Butterflies                                                               Hemitaurichthys polylepis
1 Hawaiian Cleaner Wrasse                                                     Labroides pthirophagus
1 Rectangle Triggerfish                                                            Rhinecanthus rectangulus
1 Zebra Moray                                                                        Gymnomuraena zebra
2 Red Pencil Urchins                                                               Heterocentrotus mammillatus
5 Feather Duster Worms                                                          Sabellastarte sanctijosephi

 Notes on Livestock:
I REALLY like looking for Potter’s angels while out diving in Hawai’i; and so much better when you come across the mimic Shortnose Wrasse. Why not stock them both! I’d list some other treasured endemic butterflies from the shallows of Hawai’i but they are currently not available due to the current embargo on collection there. I fully suspect the situation will be fixed in short order. The cleaner wrasse mentioned is now being aquacultured and is quite hardy, as well as exceedingly beautiful. Stick with the Rectangle Trigger, avoid the Picasso… the former stays smaller and is much more easygoing. If you don’t care for Zebra Morays for some odd reason, try the other crustacean eating Muraenid commonly found there, the Snowflake, Echidna nebulosa.
Luckily, the invertebrates mentioned can be sourced outside Hawaii; do place them amongst the lower rock to give them shelter from the fishes.

Notes on Aquascaping:
Much of Hawai’i’s shores are largely made up of broken and complete lava rock. I’d have as much rock as you can stand stacked up largely covering the bottom and back wall to good height, with occasional vacuolations/windows allowing the fish to get inside the back area.


Size: 300 Gallon FOWLR

Organisms: A Red Sea Extravaganza!                                               Scientific Name:

1 Maculosus or Asfur Angel                                                  Pomacanthus maculosus, P. asfur
2 Golden Butterflies                                                              Chaetodon semilarvatus
1 Diana’s Hogfish                                                                 Bodianus diana
1 Checkerboard Wrasse                                                        Halichoeres hortulanus
15 Lyretail Anthias (school, 1,2 males)                                    Pseudanthias squamipinnis
1 or 2 endemic Dottybacks                                                     Pseudochromis fridmani, P. springeri
1 Purple Tang                                                                        Zebrasoma xanthurum
1Naso Tang                                                                           Naso lituratus or N. vlamingii
1 Assasi Triggerfish                                                                Rhinecanthus assasi

Notes on Livestock:
Yes; there are other Red Sea Angels; the Pygoplites diacanthus (Regals) from there are fabulous and quite hardy; and there is a Centropyge and Genicanthus that might be subbed as pairs or more for the one large Pomacanthid show piece.
And there are some other Butterflyfishes, though these are rarer in the West.
Diverse Labrids hail from the Red Sea, but are either absent in western shops or too retiring to be of use.
Other, substitutions for the Purple Tang is the Sailfin, Z. desjardinii, other Nasos, N. unicornis and N. brevicornis.

Notes on Aquascaping:
Much of the Red Sea has reef slopes that look a lot like the stacked rock of many petfish aquariums; alternatively you could arrange one or both ends of a large system like this with either stacked rock and/or bommies. Do leave a good deal of space open in the front for your Angel and Butterflies, Fancy Bass, Tangs and Trigger to cruise about.





Organisms:                                                                               Scientific Name:

Notes on Livestock:

Notes on Aquascaping:



Organisms:                                                                               Scientific Name:


Notes on Livestock:

Notes on Aquascaping:



            How many variations of mixes of fish only livestock are there? Factored, it would be a HUGE number. Of course your system need not highlight an Angelfish species as a center piece; but I do encourage you to decide on such a central animal species and build your livestock assortment around it.

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: