BIg Fishy Thread

[stevie667]

In response to Actinic's post in the goldfish thread, in which he refuted my claim of a tank not being a self sustaining system, i thought i'd start up a new thread, a-because a little bit of discussion would be good for any other fishkeepers to read and b-i get to talk fish so rarely these days.

My comment of 'tanks are a self-sustaining system, but some are more self-sustaining than others' (may not be exact wording) was in reference mostly to the action of denitrifying bacteria on fish waste products and the likes, since this is what i believed the wal-mart employee's comment to most be on about.

Your 'average' fish tank is semi-sustainable on a micro scale. Often chemicals can be recycled or decomposed by bacterial or faunal elements. On a macro scale, most tanks do not have the necessary food sources to permit any sort of major fish stocking levels.

There are partial exceptions to this. For instance, i'm currently running a small nano tank in the Amano style. It has 1 fan shrimp and three otto's, all of which seem to be doing hunky dory. The plants grow at such a rate i use the tank as a nursery, taking cuttings and growing them up in there before replanting back in the original tanks.

However, the tank still requires regular waterchanges. In a natural enviroment all those animals come from areas with flowing water, providing a constant turnover. In a small (20L) tank one must change the water often to prevent build up of end level non-biological materials (such as phosphates) than will accumlate. If i replicated the tank on a much larger scale (say 2000 litres) then the water changes would likely to few and far between.

Self sustaining is a point of view.

Your go Actnic!

[actinic]

Hey Stevie...great intro to the thread

A true self self sustaining system can also be called an ecosystem, where one's waste is another's food source in equal rates of production and consumption. With the exception of compensating for evaporation, no food/nutrient is added or removed. With typical aquarium systems, there is a constant input (food) and export (physical water removal and/or chemical filtration).

Filtration systems, IMHO, are "life sustaining" equipment that are high flow, high surface area which house bacteria to convert "toxic" fish waste in a two step manner into a relatively non-toxic form. They allow higher "bioloads" for a given volume.

NH3 -> NO2 -> NO3 aka nitrification.

NH3= ammonia
NO2= nitrite
NO3= nitrate

To expand on this point, if you set-up 2 identical aquariums, one w/a filter and one w/an aerating device. One can keep more fish in the aquarium w/a filter as surface area for bacteria to live on to handle the waste is by far larger than one w/o a filter.

In the process of nitrification, an acid is produced (H+) in the first step as H is "exchanged" for O in the biological process. The buffering capacity/carbonate hardness/alkalinity (kH/alk short form) present in the water is the major component in keeping a stable pH. Once the kH/alk is depleted, the pH will drop easily to a dangerously low level where mostly fish from the Tetra and labyrinth family can survive/thrive.

The end product of nitrification is NO3. The only manner in which it can be removed is by denitrification, water changes and part of the nutrient uptake by plants/algae. High levels of NO3 in the water isn't good for fish longterm. There are more biological processes and other chemical accumulations that occur but the process of nitrification is the main one and will expand from there as need be.

The simplest manner to prevent buffer depletion and NO3 accumulation is by doing regular partial water changes. With all that to take into consideration, is a typical aquarium set-up, in whole or in part, a self sustaining system?

[stevie667]

*reading back over what he said in the first place, then goes to find chemistry notes*

Agreeing with you on the filter part, not absoloutly 100% essential to keeping fish, but pretty danged handy if you want something bigger than a bumblebee goby in a 20gal tank. I would not call very many fish tanks complete ecosystems (though i've seen the odd very advanced example).

As for the drop in hardness, what about if you happen to live in a softwater area? Apart from being on my black list for being able to keep much more in your tap water, a pH crash is still not inevitable.

It is possible to not require waterchanges due to rising nitrates. I went and did a water test on one of my big tanks, <10ppm. Considering the amount of meat related meat foods that the inhabitants get through, this is quite good. The tank is also planted to the gills.
This i always feel is the most important part of keeping fish (unless you happen to keep fish which for whatever reason don't get along with them, in which case you should be familiar with the whole set of issues anyway), without them your water will foul pretty quickly.
They will remove nitrate plus many more organic and inorganic compounds and serve to oxygenate your water. For those who feed high protein diets (like myself) a thin protein layer can accumulate, which has the potential to reduce gas exchange. Pointing your filter outlet to cause surface disruption also helps.

There are several very neat peices of kit one can get for removing nitrate from tanks, such as some of the more clever trickle filters and the likes, which will encourage bacteria that convert nitrate into nitrogen. They are often prohibitavly expensive. One can also experiment with a system of using terrestrial plants with roots dipping into a tray of flowing tank water (similar to a vegetable filter in ponds, just with nicer looking plants). These plants are excellent at taking up nitrogen compounds in the water, and if done well, can make a fish room look much nicer.

But, as actnic said, the simplest way is a water change.


I will stick with my guns and say that your 'typical' tank is in part a self sustaining system. Granted, it does help the tank to do regular maintanence, but one does not need to be doing the constant changes that would come from say, a betta in a jar. Much in the same way its a bit nicer to give your dog a wash instead of throwing him outside whenever it rains.

[actinic]

I'd like to see a pic of you planted haven . Can you tell me more of your system and your maintenance/supplement routine?

There are many ways to augment soft water parameters, whether it be off the shelf to everyday household products. Baking soda will add to the carbonate hardness and epsom salts to add to the total hardness. Some even use synthetic sea salt mix, ie Instant Ocean(TM).

Having live plants in the aquarium definitely moves to the direction of a self sustaining system, but again, another entity to keep happy and thriving. Of what I read in various aquarium forums and clients that I consult, +95% of all new aquarists begin w/o live plants.

With wet-dry/trickle filters for denitrification, I'll have to disagree on the denitrification process as their primary function is for nitrification and gas exchange. Denitrification only occurs at the sponge block after the bio-tower or the bioballs that have a centre compartment w/a sponge core where there will be an area of low oxygen. A plumbed freshwater system w/a wet/dry filtration system will add at least $800CDN including a submersible pump.

Making a vegetative filter will add to the dynamics of the aquatic system. Depending on the scale that one wishes to create:

http://www.breathingwall.com/

Perhaps I'm splitting hairs on the terminology o.O but making my hobby into a career I hope to help dispel them and come to a middle ground where everyone will understand and appreciate the complexities that make it all work.

[stevie667]

I'll try and get a pic for you, i'll have to do a bit of tidying, it doesn't look that neat atm.
It is a small 1' 20l cube (one peice of glass curved around with another siliconed to the back) with a small curved flourescent light. I actually got it free with a magazine subscription!

Sand substrate, the second from the bottom eheim aquaball filter, 50w eheim heater (i do like eheim). 1 maramo ball, bunk load of java moss, bunk load of ricca, 1 anubias, 1 crypt, 1 small grassy thing and 1 plant which has yet to be identified because it just spontaneously grew from a bit of leaf that came with the other plants. Used to have the labels but they've long since been lost. I have a small 6" peice of bogwood with ricca and java moss tied down that is actually looking very good. The only maintanence i do with that is every now and again to tie the plants down a bit tighter or they do tend to look a little straggly.

Weekly water change, fertilising with normal hagen liquid feed at recommended dose. Light for 8-12 hours a day, depending on when i turn it on in the morning and go to bed.

Plants get trimmed whenever necessary, but i mostly just let them get on with it.

3 otocinclus and 1 fan shrimp. Used to be the home of a 2" monster fish and a pair of killi's, but these have unfortunatly passed onto the big toilet bowl in the sky. I don't feed them as such, but they get a bit of flake everynow and again, or a drop or two of liquid fry feed for the fan shrimp.


I think it is an absoloute shame that people start w/o live plants, it was always something i would never let people leave the store unless they had some. But, best one can do is educate! That living wall certainly does look interesting.

My mistake as to the trickle filter, i'm thinking of something else! I will admit its been a couple of years since i was last working in the industry and i'm a little rusty on some of the more obscure technical kit. I'll see if i can find a picture of what i'm on about.

Splitting hairs on terminology is fun, there are entire discussion boards dedicated to arguing over the tiniest of things. I wish i could make a career out of fishkeeping. I've gone the otherway, try to get rich enough to buy a fishhouse so there will just be a blurry line between hobby and career