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stocking levels


Brandon

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over the past few weeks i have been doing alot of reading on stocking levels and i have found a wide range of different answers so what is the general rule of thumb that everyone feels is the best way to go

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There is no general rule like "inches per gal." that I'd put any stock in. The lighter you go the better off you are in case of power or equipment failure. In most cases (not all) a 4" inch fish is going to be 4 times the biomass as a 2" fish. I wouldn't hesitate to put a dozen 2" fish in a twenty gal. setup but it would be absurd and cruel to put a 6" or 8" volitans lion in a twenty gal setup. Deffinitely research fish before getting them and expect personality issues unless you only put one fish in.

Gabriel makes a good point! The more fish the more food. The more food aka nutrients, you're trying to process through your ecosystem the better the odds your going to have algae and cyno issues.

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Dozen 2" fish in a 20G...... that's insane!!!!!

As said there's no set limit. If you give some info about your tank, we can guesstimate to try and give you some help, but a lot of fish have different needs. Not only does the length of the fish usually exponentially increase the bioload on the system it creates, there's also the matter of how messy eaters they are, whether they swim actively, whether they need territory to hide in, whether you're running a skimmer or fuge or whatever - there's just too many VERY important details to even start getting to a rule about inches per gallon or grams per liter or something.

So what's your:

tank size?

amount of live rock?

skimmer?

fuge?

sump size?

tank maturity (age)?

current stocking?

do you have sensitive stony corals?

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well i have a 55 gallon and i am still adding live rock andi plan on about 55 lbs and i plan on getting the best skimmer i can afford but plan on dedicateing a good bit of money to that cost i dont want to go crazy with stocking i just wanted to keep things simple for now but i have been doing alot of reading that says stocking saltwater was quite a bit different so i just wanted to see what the best way to go was

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Before you start adding fish I would really plan out what you ultimately want to keep in the tank. For a number of fish the order that you add them to the tank may be important to avoid issues of aggression. Also, as different fish can create considerably different bioloads even if they are similar in size. If you plan ahead you can set your priorities so you don't run into the situation of really wanting a fish, but not being able to add it due to others you already have in the tank.

How many fish is going to be tank specific, given the equipment that you use and the bioloads and needs of the species that you pick. Once you have a plan on what equipment you will use and a list of potential occupants I think that you will find that a number of very experienced people on this site can give some good and specific feedback.

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Dozen 2" fish in a 20G...... that's insane!!!!!

That is just a matter of opinion :)

The 20g could be 24x20x10" or 20x15x15" and the concept of keeping 10-15 small fish in a layout like that (unless it's absolutely crowded with 20+ pounds of liverock..) is not far fetched. Imagine a species only tank with a school of damsels, cardinals, or chromis. You could even mix & match a dozen different gobies of 1-2" size as long as avoiding aggressive ones, and still experience no difficulties other than finding an occasional jumper on the floor. People just don't think outside of the box enough, and often don't feed frequently enough and/or give too much food per feeding.

I think people focus too much on the number of fish per volume. People think a 55g tank, and they picture a 48x12" footprint, rather than a 24" cube. In the cube, there is enough space for some fish that would otherwise not fit comfortably & happily in a long narrow tank with it's girth crowded by a long wall of rock.

An aquarium should be stocked based on what kind of health and longevity you can provide the fish with.

- If you are considering fish that are grazers by nature, and have a high metabolism - do not put them in a tank that only eats once a day. (Only keep fish you can maintain the appetite of)

- If you are not equipped with a fuge, adequate skimmer, or a nitrate reactor - do not stock the tank with grazers, and feed them many times a day. (Only feed as much as you can clean up after)

- If you're keeping a variety of coral that only thrive in a brightly lit environment, and have a high-powered light over the tank - do not put skittish fish, collected in deeper waters. (Only keep fish that will thrive in your temperature and light environment)

- If you plan to have many fish in the tank, that are constant active swimmers - do not keep shy/solitary/cryptic fish. (Only keep fish that will be comfortable & compatible with one another)

- If keeping fish that are famous for not accepting prepared foods, do not stock multiples that will compete for the same limited food-source. (Only keep as many as you can DEFINITELY sustain the appetite of, NEVER MORE)

Realize that your aquarium is a habitat, or environment, that you are responsible for. When a Tang eventually gets too large for your aquarium, or begins fighting with similar inhabitants, or keeps getting skinnier and skinnier over time - only YOU are to blame, not the fish. You are the one responsible for where the fish is today, and the condition that it's in. Only purchase fish that you are SURE you can maintain, as it's not just money lost when you lose a fish. I hope this is read as considerate and helpful, rather than ranting and fish-nazi :D

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I agree with all your points, but keeping a dozen even very small fish (aside from fry) in a 20G tank would mean needing a skimmer, running carbon or another chemical media, and a huge amount of live rock to keep your ammonia below 5ppm :( Maybe if you had a 40G sump connected to it you could keep things in line, but then it's not really a 20G tank. I know virtually the smallest schooling fish would also be impossible to keep in a tank that size because they need a near continuous food supply to stay alive (we're talking more than 4 feedings per day). Also going even with peaceful gobies generally makes problems, because gobies and blennies of the same body shape will often fight with each other, and of course non-paired ones of the same species would also fight. I've also heard the opposite about cubes, that some fish which like to swim a lot do better with one long dimension (for a straight swimming path) than in the equivalent cube tank, but I don't have experience with that, just what i've heard. I just don't see a way that those numbers in that small a tank could work.

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Pair of perculas, 2-3 Royal Grammas Flame Hawk, couple of Ranfordi gobies, 4-6 fire gobies and a Zebra Goby. I don't see a problem with that at all in a twenty gallon system and I wouldn't see a need for than 4-6 pounds of liverock. I would probably do a weekly or biweekly 5 gallon water change and probably would run carbon but don't see that I'd need more than a cup a month.

Good points Randy.

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..keeping a dozen even very small fish in a 20G would mean needing a skimmer, running carbon/another chemical media, and a huge amount of live rock to keep your ammonia below 5ppm :) Maybe if you had a 40G sump connected to it you could keep things in line, but then it's not really a 20G tank.

I never advocated trying to cheat and make a system of beyond 20g with only a 20g display tank - but I don't think that a 20g would need anything beyond, say, a 2217 or 2227 filter on it (avoids frequent filter cleaning and the need for powerhead) and about 8-12lb of liverock to give all your different fish territories. Sure, a 5g waterchanges every 10-15 days, but that's no daunting task since I know many customers who already do this on their 20-35g tanks that don't even need it that frequently. No skimmer necessary unless you're feeding a staple diet of frozen food - but smaller less delicate fish typically wean onto pellet pretty easily, so why not set up an autofeeder to drop a minute amount of food in 4x a day? Done. Anyone that thinks that is nuts hasn't tried it, but like I said, I'd never stick fish in that small a space unless they were able to cohabitate without quarrel.

..the smallest schooling fish would also be impossible to keep in a tank that size because they need a near continuous food supply to stay alive (we're talking more than 4 feedings per day). Also going even with peaceful gobies generally makes problems, because gobies and blennies of the same body shape will often fight with each other, and of course non-paired ones of the same species would also fight.

While I do have a skimmer, I certainly don't have any chemical/media form of filtration to make up for my feedings - and I feed well beyond 4x/day (and never even hit 20-25 nitrate, nor have I/do I register any ammonia or nitrite). You have to be smart about feeding - know how much to apply per feeding, how many times to feed per day, and what foods to/not-to use. Like I said, feeding pellets and flake every day will make for a cleaner tank and less need for skimming/carbon, but if relying on frozen foods you will certainly need to rinse them well before feeding, as well as use carbon or a skimmer. You're probably thinking of gobies that are inopportune for mixing. Having a nano yourself, I presume you're pretty familiar with gobies that AREN'T sand dwellers, and AREN'T jumpers. There are a lot of small options out there, well under that 2" mark, that wouldn't quarrel in close quarters (well, beyond 10-15g) because they don't eat very much, move very much, or have a very competitive or dominant demeanor. When you get into sand-dwellers, its a whole 'nother story, and I suggest avoiding mixing them at all costs - you'll just end up with one jumping.

I've also heard the opposite about cubes, that some fish which like to swim a lot do better with one long dimension (for a straight swimming path) than in the equivalent cube tank, but I don't have experience with that, just what i've heard.

I did say that the cubed dimensions would only work better for SOME fish, but when dealing with custom tanks, you're really not limited to anything. For the sake of the 55g argument, it could be a 48x12x20, or a 48x18x15, or 36x24x18, or even 40x40x10" :lol: Just for the record, long & skinny isn't always best, and while a longer/larger fish will certainly want to be able to dart in one direction without interruption, that same fish isn't comfortable darting back and forth down a narrow stretch with nowhere else to turn.

Compare it to couping your dogs up in a part of the house, when you're at work. Would you close your adult Great Dane in a long narrow hallway, that might have some decorative pots along one wall? Or would you rather he was in a wider, but shorter, rectangular or square bedroom? If you had 10 3-5lb puppies, would they be better suited to be in a 12x4' area, or a 8x9' area?

FWIW, I'm not arguing, just helping the conversation move forward. I really promise that most people do NOT think out of the box - whether it's what fish 'can go together' versus 'would do exceptionally well together', or their diets, or fitting a fish to a tank. This is a healthy conversation, and I hope you're not taking this as snippy :doh: I can tell you that my 150g has 3 Butterflyfishes, 5 Angelfishes, 10 Cardinals, and a Wrasse (and til this weekend, a Moorish Idol). I feed nori/algae 2-3x a day, pellet 2-4x a day, and frozen 3-4x a day - and sometimes more on the weekends. I just make sure to never introduce any more food than will be immediately eaten, and often the fish are left having had something, but not enough to be full. They're all actively and readily eating directly out of the net, or biting at the syringe/baster, and I seriously have the most lax maintenance regimen you can imagine. Feeding my fish MANY times a day, in very small controlled doses allows me to avoid all their aggression, and to avoid getting any sort of waste build up. My skimmer doesn't exactly go crazy, but I've never tested out with an undesirable amount of ammo/nitrite/nitrate - and I'm still adding more fish to the equation. For those on the side of "you can't fit that many fish in that size tank" or against mixing certain types of fish with one another, you should really branch out and start viewing some of the Japanese tank blogs, they'll blow you away with how much harmony and balance they achieve with insane amounts of fish, unbelievable #'s of feedings, and never a speck of algae (and without being invested in many thousands of dollars in equipment). To each his own, of course, but thinking outside the box is definitely a good and fresh thing for this type of hobby.

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....alright....

I've got 2 nanos, a 7.5G and a 24G and I'm currently running about 1/4 of the stocking (or less, considering full grown fish size) and I just can't picture that many fish in any tank this small. I've done a lot of reading on nanos and I still can't picture it working out, yes they're small fish but their waste builds up quickly. Perhaps the recommended 5 gallon biweekly water changes could do it, but I for one don't want to be switching out 50% of the water every week - that sounds more akin to raising fry anyways. Also having less live rock may mean more swimming space, but it also means drastically reduced biological filtration capacity. I suppose in a FOWLR this can be solved (at least somewhat) with mechanical filtration, but still it doesn't seem to indicate healthy living conditions to me. Maybe it's just that while I can see a dozen fish in 20G of freshwater, it's difficult to find marine fish that are small enough to do that. Even a firefish - by no means a big fish, though not the smallest - is closer to 2.5-3". Neon gobies would be small enough, but you wouldn't be able to keep more than 2 or 3 pairs in there without territory fights - same goes for most of the very small gobies or blennies.

This guide may be a little bit on the conservative side (it is a beginner's guide) but it's recommending 1/4-1/3 of that stocking level:

http://www.nano-reef.com/forums/index.php?showtopic=74703

Also the dog comparison seems silly to me, it's much more difficult for a dog to take up any space in the height direction, so obviously the square feet is what matters and the height is thrown out of the equation above a minimum level.

I suppose this discussion should probably have it's own topic.... oh well.

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Sooo, Brandon, hope this thread has helped clarify things for you! :)

Has anyone seen recommendations based on weight of the fish to weight of the water in the system or volume displaced by fish to volume of water?

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I know its a little late for you but for when you upgrade(which you will with a 55 gallon, trust me- I did a 65, to a 180, now a 360) I would suggest writing and researching all the fish you would like to keep in a tank then base your tank size around that. I am guessing you are relatively new, so I cannot stress enough the research that goes into every purchase. There is massive amounts of info on here and other places on the web which will help tons. Feel free to ask questions as everyone encounters problems in this hobby and most likely someone else have overcome your issue and can help you through it. Happy Reefing!

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