The IFU Biomass Measurement: The Base Unit of the Fishsheet

For those wondering what biomass is and how the Fishsheets calculate biomass.
 
 
 
Biomass, for the purposes of HMF, is the quantity or mass of a biological entity that produces a biological effect. In other words, biomass is a calculation that tries to assess the proportional impact of an animal or plant using or approximating one or more of its physical properties. Nearly all stocking guidelines address biomass, but they differ from the Fishsheets in how they measure biomass. Most common stocking rules measure biomass using length; most rules assume that the biological impact of a fish is proportional to its length. Using length alone means that a fish that is twice as long as another fish will have twice the biomass of the other fish, but this is not necessarily true. Consider the following diagram:
 

If two fish have the same body proportions, then their difference in biomass will be more accurately assessed by taking all of their basic dimensions into consideration. Consequently, a fish that is two times longer than its counterpart will also be two times wider and two times higher, a net effect of having eight times more biomass. To account for this multi-dimensional view of biomass, the Fishsheets originally cubed the length of each fish that was entered into them and compared that displacement to a standard displacement. The basic formula looked something like the following:

Biomass = A*A*A = A^3 Where A is the adult length of the fish in question.

 
These new units were called IFUs (Ideal Fish Units) and could account for a much greater range of fish sizes than other stocking rules in that they required no transition to switch between large and small fish. Some of the common stocking rules have different sections based on the length of the fish. These sections require the aquarist to use different computations depending on the length of the fish. IFUs, contrarily, require no such adjustment as the proportionality difference is implicitly accounted for.
 
Nonetheless, the above cubic relationship proved inaccurate for very small fish and very large fish. Why? The impact of a fish on its environment depends on more than just a dimensional comparision. Other factors include the unique proportions of each fish and on the oxygen needs of each fish. Account for each species' unique habits requires the use of a family-specific coefficient (f), but accounting for oxygen use requires a little bit of abstraction:
 
Volumetric Biomass = f*A*A*A = f*A^3
Surface Area Available for Oxygen Absorbtion = F*A*A = F*A^2
 
Surface Area per Volume = F*A^2/(f*A^3) = (F/f)*(1/A)
Surface Area per Volume Applied to Volumetric Biomass = (F/f)*(1/A)*f*A^3 = F*A^2
 
Comparing the the two means of measuring biomass it becomes evident why the old IFU calculation did not work well for very small fish or very large fish: Compared to the new formula, the old formula was way too small for little fish and much too large for bigger fish. Now the Fishsheets use the more moderate F*A^2 calculation. This new hypothesis that compares oxygen requirements is called the SAVI adjustment (Surface Area and Volume Integration).
 
Nonetheless, there is a question that does occassionally come up: What about the metabolism of young fish? For instance, a young Silver Dollar and a full-grown  Black Skirt Tetra are similar in size, shape, and habits, but does their similarities in size and species negate that one is much younger than the other? No, the Silver Dollar will have a greater biological impact because its metabolism will be higher. It is still growing and will require more food, oxygen, and space than its aged cousin. Most of the new fishsheets do address the current size of the fish but may use a variety of equations to do so.
 
Currently, the Fishsheets use species-specific biomass measures that are as follows (adjustments are made for male/female, etc):
 
Species Size (in.) IFUs IFUs/in.
BICHIRS
Cuvier, Senegal Bichir, Dinosaur Eel 14.00 319 22.8
Ornate Bichir 24.00 932 38.8
BUTTERFLY FISH
African Butterfly Fish 4.00 25 6.3
CATFISH, CORYDORAS
Adolfo's Cory   2.20 9 4.1
Agassizi Cory    3.20 29 9.1
Bandit Corydoras         2.00 8 4.0
Bronze Corydoras 2.75 18 6.5
Dainty Cory      1.20 3 2.5
Dwarf Corydoras  1.20 3 2.5
Elegant Cory     2.00 9 4.5
Emerald Catfish                  4.00 35 8.8
False Julii Corydoras 2.50 16 6.4
Giant Brochis                    4.10 38 9.3
Julii Catfish                    2.00 9 4.5
Panda Cory 2.10 10 4.8
Peppered Corydoras 2.30 10 4.3
Sixray Corydoras, False Corydoras 1.10 3 2.7
Skunk Cory       2.00 10 5.0
Xingu Corydoras          1.75 8 4.6
CATFISH, GENERAL
Banjo Catfish    6.00 59 9.8
Bumblebee Catfish 3.20 18 5.6
Flagtail Catfish                         3.30 17 5.2
Glass Catfish 3.00 14 4.7
Iridescent Shark (Pangasius) 36.00 4620 128.3
Raphael Catfish          7.75 126 16.3
CATFISH, GENERAL HERBIVORE
Bristlenose, Bushynose Pleco 5.45 55 10.1
Butterfly Pleco L-168 6.15 70 11.4
Clown Pleco      3.40 31 9.1
Common Pleco 22.00 1099 50.0
Gold Nugget Pleco           6.60 108 16.4
Marbled Whiptail         7.35 38 5.2
Multiradiatus Pleco      19.00 1027 54.1
Otocinclus Affinis 1.75 6 3.4
Rubberlip, Bulldog Pleco 4.00 32 8.0
Sunshine Pleco                   11.50 300 26.1
CATFISH, LARGE PREDATORS
Pictus Catfish                           4.40 63 14.3
Porthole Shovelnose Catfish 21.00 1273 60.6
Shark, Silver-Tipped Shark Catfish 24.00 2043 85.1
CATFISH, UPSIDE DOWN AND SYNO.
Angel Squeaker   9.85 217 22.0
Brichard's Synodontis  6.45 72 11.2
Cuckoo Catfish   6.00 88 14.7
Ocellated Synodontis     13.15 391 29.7
Upside-Down Catfish              3.90 37 9.5
CHARACINS, HATCHETFISH
Marbled Hatchetfish 2.20 14 6.4
Silver Hatchetfish 2.70 20 7.4
CHARACINS, HEADSTANDERS
Leporinus 11.00 218 19.8
Marbled Headstander      5.15 57 11.1
Striped Headstander      7.00 60 8.6
CHARACINS, PACU
Black Pacu       39.00 14688 376.6
Red Bellied Pacu    38.00 11096 292.0
CHARACINS, PIRAHNA
Red Bellied Piranha 13.00 682 52.5
CHARACINS, SILVER DOLLARS
M. Argenteus 6.15 195 31.7
M. Hypsauchen 5.85 185 31.6
M. Maculatus 7.35 234 31.8
CHARACINS, TETRAS
Black Neon Tetra 1.60 6 3.8
Black Skirt Tetra 2.40 19 7.9
Bleeding Heart Tetra 3.40 33 9.7
Blind Cave Tetra 3.20 29 9.1
Bloodfin Tetra 2.15 8 3.7
Bucktoothed Tetra        5.50 79 14.4
Buenos Aires Tetra 3.10 21 6.8
Cardinal Tetra 2.00 9 4.5
Columbian Tetra  2.10 11 5.2
Congo Tetra 4.00 41 10.3
Dash Dot Tetra 1.60 5 3.1
Diamond Tetra    2.50 17 6.8
Emperor Tetra 2.25 13 5.8
Flame Tetra 2.00 10 5.0
Garnet Tetra                     1.50 5 3.3
Glowlight Tetra 1.70 7 4.1
Gold Tetra 2.00 9 4.5
Head and Tail Light Tetra 2.00 11 5.5
Lemon Tetra              1.90 10 5.3
Neon Tetra 1.40 4 2.9
Penguin Tetra                            2.90 18 6.2
Red Eye Tetra            3.00 22 7.3
Rosy Tetra       1.70 9 5.3
Rummy Nose Tetra 2.00 10 5.0
Serpae, Red Minor Tetra 1.65 7 4.2
Silver Tip Tetra 2.00 7 3.5
Splashing Tetra  2.20 6 2.7
CICHLIDS, ANGELFISH
Yes 6.20 168 27.1
CICHLIDS, DISCUS FISH
Yes 9.30 385 41.4
CICHLIDS, LARGE (>5.5 in.)
Black Belt Cichlid 13.35 606 45.4
Blue Acara       8.00 231 28.9
Firemouth Cichlid 5.95 113 19.0
Five-Bar Cichlid                         5.95 90 15.1
Flag Cichlid 7.35 170 23.1
Flier Cichlid    7.00 169 24.1
Frontosa Cichlid                         13.85 728 52.6
Green Terror                     10.60 399 37.6
Jack Dempsey 9.50 276 29.1
Jaguar Cichlid                   20.00 1352 67.6
Jewel Cichlid                    5.85 100 17.1
Midas, Red Devil Cichlid 14.00 744 53.1
Oscar            14.00 681 48.6
Red Terror               17.00 947 55.7
Rostratus                11.90 461 38.7
Severum          9.25 374 40.4
Wolf Cichlid             26.00 2547 98.0
CICHLIDS, SMALL (<5.5 in.)
African Butterfly Cichlid, A. Thomasi 3.25 31 9.5
Agassiz's Dwarf Cichlid 3.05 23 7.5
Aulonocara Benga         4.50 68 15.1
Aurora Cichlid   3.85 46 11.9
Banded Dwarf Cichlid 2.40 12 5.0
Black Banded Sunfish 4.00 59 14.8
Blue Zebra Cichlid                5.20 88 16.9
Blunthead Cichlid                        5.45 93 17.1
Bolivian Ram Cichlid 3.05 23 7.5
Brevis Shelldweller                     2.30 16 7.0
Cockatoo Dwarf Cichlid 3.50 26 7.4
Convict Cichlid 5.50 100 18.2
Cylinder Cichlid            4.90 58 11.8
Demason's, Demasoni Cichlid       3.15 31 9.8
Dwarf Flag Cichlid 2.90 24 8.3
German Blue Ram 2.55 18 7.1
Julie (Convict), Regani Cichlid 5.05 58 11.5
Kenyi Cichlid 5.25 86 16.4
Keyhole Cichlid                  4.60 58 12.6
Kribensis 3.85 45 11.7
Lake Malawi Cichlid           5.00 70 14.0
Lemon Cichlid            4.15 46 11.1
Lionhead, Humphead Cichlid                 4.80 57 11.9
Mbuna       4.90 67 13.7
Viejita Dwarf Cichlid 3.00 22 7.3
CRABS  
Fiddler Crab (Brackish) 2.00 45 22.5
Red Claw Crab (Semi-Brackish) 2.90 127 43.8
CYPRINIDS, BARBS
African Spotscale        4.70 57 12.1
Arulius Barb 4.75 48 10.1
Blue-Barred Barb 2.25 10 4.4
Checkered Barb 2.00 10 5.0
Cherry Barb 1.85 7 3.8
Congo Barb       3.10 16 5.2
Denison Barb 5.40 58 10.7
Dwarf Barb       3.00 23 7.7
Gold Barb                      2.95 23 7.8
Rosy Barb 5.50 90 16.4
Ruby Barb 2.60 20 7.7
Spanner Barb     7.00 138 19.7
T-Barb                           7.00 138 19.7
Tiger Barb 2.85 26 9.1
Tinfoil Barb 14.00 602 43.0
CYPRINIDS, DANIOS
Chela Dadiburjori 1.35 3 2.2
Giant Danio 4.60 39 8.5
Glowlight Danio 1.45 5 3.4
Pearl Danio 2.20 12 5.5
Queen Danio              3.05 16 5.2
Zebra Danio 2.15 9 4.2
CYPRINIDS, MISCELLANEOUS
Chinese Algae Eater (CAE) 10.65 243 22.8
Flying Fox 6.00 76 12.7
Goldfish, Common 15.00 737 49.1
Goldfish, Fancy 6.35 352 55.4
Goldfish, Koi 36.00 14671 407.5
Goldfish, Shubunkin 11.00 316 28.7
Rosy Minnows 2.85 15 5.3
Siamese Algae Eater (SAE) 5.60 47 8.4
White Cloud 1.65 7 4.2
CYPRINIDS, RASBORAS
Axelrod's Rasbora 1.30 3 2.3
Greater Scissortail Rasbora               6.05 54 8.9
Harlequin Rasbora 1.85 10 5.4
Hi-Spot Rasbora                  2.40 11 4.6
Red Dwarf Rasbora, M. Rubescens 1.20 4 3.3
CYPRINIDS, SHARKS
Bala Shark 15.00 589 39.3
Black Shark 26.00 1856 71.4
Chinese Banded Shark 36.00 5332 148.1
Rainbow Shark 6.00 65 10.8
Red-Tailed Shark 6.00 55 9.2
ELEPHANTFISH
Baby Whale 8.00 113 14.1
Elephant Nose    11.00 176 16.0
GLASSFISH
Giant Glassfish                  9.80 274 28.0
Indian Glassfish        3.05 23 7.5
GOBIES
Bumblebee Goby   1.65 12 7.3
Fandancer, Knight Goby 3.50 47 13.4
FROGS, AQUATIC
African Clawed Frogs 4.85 106 21.9
African Dwarf Frog 2.20 28 12.7
KILLIFISH
Amiet's Lyretail  2.75 10 3.6
Clown Killifish 1.60 3 1.9
Flagfish                                 2.30 13 5.7
Golden Wonder Killifish 3.95 25 6.3
Redchin Panchax          2.45 8 3.3
Striped Panchax 3.95 25 6.3
KNIFEFISH
African Brown Knifefish, X. Nigri 12.00 301 25.1
Clown Knifefish  40.00 8322 208.1
Ghost Knifefish 22.00 1092 49.6
LABYRINTH, BETTAS
Female Siamese Fighting Fish 2.65 13 4.9
Male Siamese Fighting Fish 3.20 15 4.7
LABYRINTH, CLIMBING PERCHES
Spotted Ctenopoma        7.05 153 21.7
LABYRINTH, GOURAMIES
Blue, Two Spot, Opaline, Gold Gourami 4.75 50 10.5
Chocolate Gourami        2.45 17 6.9
Dwarf Gourami 2.40 18 7.5
Giant Gourami                    28.00 4642 165.8
Honey Gourami                    1.85 10 5.4
Kissing Gourami 10.90 203 18.6
Moonlight Gourami        5.65 72 12.7
Paradise Fish 3.80 18 4.7
Pearl Gourami                  4.20 40 9.5
Snakeskin Gourami 8.35 144 17.2
Thick Lip Gourami           3.70 36 9.7
LIVEBEARERS
Guppy 2.10 8 3.8
Halfbeak, D. Pusilla 2.75 8 2.9
Molly, Black Molly 3.55 30 8.5
Pike Livebearer 6.55 64 9.8
Platy, Moonfish 2.10 12 5.7
Sailfin Molly 5.15 70 13.6
Swordtail 5.05 64 12.7
LOACHES, GENERAL
Angelicus Botia 4.20 24 5.7
Blue Loach       9.10 146 16.0
Burmese Loach    4.20 24 5.7
Dwarf Chain Loach      2.25 8 3.6
Chinese Hillstream Loach, Butterfly Pleco 2.70 24 8.9
Clown Loach      16.00 520 32.5
Skunk, Cream Loach      4.00 51 12.8
Yoyo Loach               5.70 57 10.0
Zebra Loach              3.85 27 7.0
LOACHES, EEL-LIKE
Banded Loach     8.25 110 13.3
Bengal Loach     6.00 45 7.5
Horseface Loach                  9.95 112 11.3
Kuhli, Coolie Loach     3.80 14 3.7
Mottled Loach    4.15 16 3.9
NEWTS
Chinese Fire-bellied Newt 3.65 38 10.4
Japanese Fire-Bellied Newt 5.15 75 14.6
PUFFERS, BRACKISH
Spotted Green Pufferfish                         6.70 223 33.3
PUFFERS, FRESHWATER
Dwarf Puffer     1.15 7 6.1
Mbu Puffer 26.00 4845 186.3
RAINBOWFISH
Australian Rainbowfish 4.00 49 12.3
Bleher's Rainbowfish    4.70 59 12.6
Boesemani Rainbowfish 4.10 49 12.0
Celebes Rainbowfish 2.85 13 4.6
Dwarf Blue Neon Rainbowfish 2.35 15 6.4
Madagascar Rainbowfish           5.95 71 11.9
Red Rainbowfish 5.55 107 19.3
Threadfin Rainbowfish 1.65 6 3.6
SHRIMP/CRAYFISH
Amano Algae-Eating Shrimp 2.00 6 3.0
Cherry Shrimp 1.50 3 2.0
Crayfish, Blue Lobster, Tiger Lobster 4.65 51 11.0
Flower, Bamboo Shrimp 3.80 19 5.0
Ghost Shrimp 1.50 3 2.0
SNAILS
Apple, Mystery Snails (Ampullariidae) 6.00 75 12.5
Malaysian Trumpet Snail 0.80 2 2.5
Ramshorn Snail 1.00 3 3.0
SPINY EELS
Peacock Eel 11.30 151 13.4
Ropefish 28.00 973 34.8
Tire Track Eel   34.00 1875 55.1
 
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