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Cycling a tank with damselfish?

AlanR917

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Feb 21, 2013
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Wausau, WI
Hello everyone. I have heard from multiple sources, and done some online research that damselfish are good starter fish to help cycle the tank before the octopus is added, and may even help speed up the process. Have any of you used this method? Does it work? I feel this would be safer than using bacteria-starter chemicals, but dont want to kill the damselfish if it doesn't work very well. Thank you!
 
Would you rather use hermit crabs, or damselfish? I just figured that I could put a damselfish in and have something cool to look at while the bacteria was growing and everything was cycling. What would you recommend?
 
I am a major opponent of using fish to cycle an octopus tank. Many object because often the fish die in the cycling process but my objections are outside of any cruelty issue. Any fish hardy enough to aid in cycling will be an aggressive meat eater. They are very difficult to catch and you will end up disrupting your tank trying to do so. Because of the extreme difficulty and disruption, many people decide to "just leave it in there for food". This leaves a territorial, aggressive animal in the tank and no good ever comes of it. Sometimes the octo will be large enough and fast enough to kill the annoyance (sometimes eating part of it, sometimes not) but it is a stressor for the animal and will be a negative and unhealthy experience. If the fish survives, it is almost guaranteed to pick on the octo and can cause skin damage (eyes are always a concern here but we have not seen them blinded) that can lead to infection.

There is an adage that enthusiasts learn to be true, "Nothing good EVER happens quickly in a saltwater aquarium". We try to encourage you NOT to learn the hard way and emphasize a slow, and thorough cycle. You can't "see" that a tank is cycled and you will have to accept that it is a slow process to build up the beneficial bacteria that will convert the excessive waste from ammonia (deadly) -> nitrite (also deadly) -> nitrate (benign in small quantities). The biological process the bacteria provides will keep your tank from killing the animals. Water changes, good cleaning habits and good water flow will help remove the final stage of pollution. To build up enough waste, you need to feed the tank and have the waste go through the conversion process.

Porous rocks are a preferred substrate for housing and growing the bacteria. The introduction of live rock (rock that already has bacteria growing) is favored by many and will speed up the process. Artificial addition of bacteria (if what you buy is actually alive, often not the case) will only temporarily increase the desired level but if the tank is not well established, it will simply die off. Cycling a tank requires feeding it to slowly build the beneficial bacteria to stable levels. Another heavily experienced problem is commonly expressed as, "new tank syndrome" (look up both terms, you will find them prevalent through out the forums). This is a result of overloading a new tank with animals before there is enough stable bacteria to quickly convert the waste. You should actively feed a tank for a minimum of 3 months before thinking about adding an octopus. Octopuses produce a lot of waste and an uncycled or minimally cycled tank will become poisonous quickly.
 
Thanks DWhatley! A few more questions while you're online.

1) If I put live rock in my tank after it is filled, how much waste would it produce? Would the skimmer need to be changed often? We are going out of town for about 10 days, and I was contemplating whether or not to wait until we get back to fill it up? I would like to fill it up before, so the tank has longer to cycle, but am not sure if I should put the live rock in?

2) I've heard of putting part of a shrimp in the tank to help cycle it and establish bacteria. Would this help if I have 50 lbs of live rock or will the LR be enough?

Thanks again!
 
I would go ahead and set it up before you leave. The first few weeks really don't need attention at all and are very boring (well, until you learn to look for little cool things anyway). You can leave your skimmer off during this time (many people recommend doing so even if they are there to clean it). Definitely put the LR in the tank (it is not alive if it is dry now). Some people will cycle for a month or more with just the rock and the water and then arrange the rock and add sand and a few crabs after the first month. True live rock will have a lot of die off when it is initially placed in the tank and this will feed the bacteria at the beginning stages.

I have never tried the shrimp cycle and have read conflicting comments about its effectiveness so I would suggest reading (we do a lot of that in the marine tank hobby) about the process. From what I remember (keep in mind I have not cycled a fully new tank in several years) the process is simple but you do have to refresh the shrimp from time to time. Probably the most important initial steps are getting good live rock. Really fresh rock (along with feeding it and adding critters to consume the food and produce waste, starting with animals like hermit crabs and building to serpent stars and urchins and then to some of the octo safe filter feeders like gorgonins) will be the key to how successful you initial and on-going cycle progresses. A tank is never fully "cycled" as the process is on-going but having it take on a bio-load and not become poisonous is the initial goal. IME it takes about 5 years for a tank to mature and by then you have to fight nitrates (the end result of the nitrogen cycle). I am always amazed with I see something new growing in the rocks that seem to show up spontaneously. Some of it comes from dormant "stuff" in the rock, other things likely come from something else I intentionally placed in the tank but now survive because the environment is stable. I recommend getting a magnifying glass. Not a strong one, they are too hard to focus but something between 2 and 5 x. It should help make your tank a bit more entertaining while you are fighting impatience. If you are typical :wink: you will panic slightly when you see your first explosion of little white "bugs" all over the glass. If you have access to a camera with a macro lens, experiment with it as you see little things. If no macro lens is available, rig the recommended magnifiying glass to the front of the tank and take pictures through it, then review them on the computer to see what is alive in the tank. You may not be interested in doing this a lot but it is a fun rainy day exercise and you will start to understand that the whole tank is alive.

I don't understand you question about the amount of live rock. 1.5 pounds per gallon is a happy medium. Some will say 1 pound is a minimum and other 2 pounds/gallon as optimal. A lot depends on the quality and porosity of the rock. You do want to place it so that it gets maximum water and flow exposure. Even in the final set up you want to strive for as much exposed surface as you can manage and still have the rock work stable and aesthetic. Moving water behind the rock is beneficial for both removing debris and keeping it alive. I use Koralias placed in mesh bags and stuffed behind each end of the LR to aid water movement. With an unoccupied tank, any pump works well but you need something octo safe in the final set-up.
 
I am out of my comfort zone trying to guide initiating a wet dry filter. On one hand, you want to get the bacteria started but on the other, the initial die off of the live rock may produce more nitrate creating junk than is optimal for startup. Do you have a filter sock you can use at the point where the flow enters the tank (I think I remember you were going to put something in front of the wet-dry to collect detritus)? If you are prefiltering then I would think running everything but the skimmer would be the best arrangement. DO be sure any filter sock/material you are using will overflow INTO the sump and not overflow to the floor.
 
When the flow enters which tank? The main tank or the sump (2nd tank)? I was going to have a filter pad (or whatever they're called) on the top of the bio ball container, so it is semi-filtered of big clumps when it enters the bio balls. Is this what you mean?
 

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