The Puffer Forum

Hey guys, I am just curious & asking for the sake of knowledge,
How are gallons per fish determined? I have often heard the rule of freshwater fish it is one gallon per inch of fish, saltwater is five gallons per inch. I am not sure how true that even is, but puffers clearly do not follow it... I'm asking mostly because I was reading about fahakas the other day, & saw they can get up to 18" & need 120+ gallons. The puffer of the day, bullseye puffer, is smaller, 17", but needs 180. Does anyone know why or how we come to these measurements?
Just wondering

RTR would be better able to handle this Q but the basic theory is:
A fish will produce X amount of waste. That X will equal your nitrate levels or bioload. If your tank is getting 20+ on that reading doing weekly water changes of 50% then your tank is over stocked, thus the need for a larger tank.

If you are doing less than 50% weekly than you will need a larger tank. If the fish needs more room to roam, you will need a larger tank.

The tank sizes specified take all this into consideration. When choosing a tank, think what the minimums, are and go +30 ~ 50%. Substrate and structure take up volume and that is usually in the area of 25 ~ 30% for FW, more if it is SW.

+1
When dealing with puffers and other largish fish, I take the maximum adult size, and for length of tank go 4x-6x that max size, and about 2x - 3x for the width. So for Balki, his max adult size can reach 7". His tank is 40" L x 16" W
However, if he does get 7", he's getting a bigger tank, I'd rather him have more space at that size.
The females are larger, but cuvier bichirs can reach 12". Mortimer grew really quickly and has stayed right about 9". His tank is 48" L x 18" W. He's more flexible than most fish though .

That 1" per galllon rule isn't really a realistic rule at all, it really could only be applicable to tiny slim bodied schooling fish.

Both the above posts are effectively correct.

The antique one inch per gallon body length rule is absurd mythology. A fish's bioload is a reflection of its mass and heavily influenced by its eating habits and lifestyle. When you increase length of a slender-bodied fish, a doubling of length produces a fish with ~4x the mass at least. Heaviy-bodied fish such as puffers (and Oscars and many other Cichlids and Scats and some catfish) increase mass significantly more than 4x with doubled length. Plus you have to add extra water volume to make up for their extremely messy eating habits. That old "rule" was intended for mixed tanks of small schooling fish, never for specimen or species tanks of predators. Puffers are not ever "mixed tank" fish anyway.

The PufferPedia minimum tank sizes are based on pragmatic experience from experienced hobbyists who have worked with the fish or in some cases with similar closely related fish with similar temperament. But do remember that those are minimum sizes and that "minimum" is never synonymous with "optimum", which would be at least 50% larger than the minimum and better 2x the minimum.

The tank nominal volume also may need modification for the tank's configuration and the fish's normal activity. Long, slender or sinuous fish may be okay in a tank where the depth (which for tanks is front-to-back distance) is at least 2x the fish's maximum adult length. That would be for fish such as Kuhli loaches to Arowanas. Stubbier or more heavy-bodied fish (such as most puffers) do better with 3x max. bodt length depth, to accommodate turning.

The tank width (end to end, more rationally it's length) can vary from 6x the fish's max. adult length, to accommodate normal swimming. The shorter tanks are suited to relatively inactive puffers, the longer size to fast and active swimmers. That figure is really too small for hyperactive fish or for schoolers. (only one FW puffer is a schooler in the wild other than for seasonal migrations, but a number of BW and SW puffer do this but not at hobby-tank scale). The height of the tank provides some needed swimming space, but its relation to the depth and width is generally an aesthetic and/or a utilitarian choice (tanks over 24" high are difficult to work in).

The mass of decor and substrate also reduces working (actual) water volume in the tank. FOWLR for SW markedly reduces water volume, as does other bulky decor in FW, BW, or SW. That has the functional effect of concentrating waste and thus requiring more frequent or larger partials, or the use of sumps or refugia to increase working volume between the two linked tanks.

HTH

1"/g is for a 1" long, streamlined fish, like a neon tetra. Nothing else.

good thread this is the kind of stuff i like to read. really good things to know. i would never think of looking something like this up. its great to stumble upon.

RTR, thank you so much for all that information! It's good to know. I really do appreciate your taking the time to answer. I think "why" questions are the most important ones, but they tend to be a pain in the butt to answer. Thanks also JP, Seven, & PP

DrK, I like to think & learn. it may not be absolutely essential to know this stuff to operate an aquarium, but it definitely is helpful in understanding why it is we do what we need to do.

That is a hold-over from my lab days. If everyone knew and understood what they were doing and knew why they were doing it a well, my life was easier. Also our work went more smoothly and far better. Understanding why is to me a basic need.

thank god the dreaded "how" question wasn't asked

There is a lot of temptation when providing optimum tank size for a single puffer fish because many people want to add more fish to fill up all the extra space. I started with "a single puffer per tank". I'm upgrading all my tanks to 40+gals and I'm having a hard time keeping the same mindset.

Very few puffers are suited for other than species tanks. In limited water volumes, that jut do not work well. They are always a danger to tankmates, and the stress shortens their lifespan as well.