Cycling with fish

diademhill · Posted: Thu Jun 21, 2007 12:15 am Post subject: Cycling with fish

Cycling With Fish.

We all recommend that no fish are put through the stresses & toxicity of a cycling tank and that new tanks should be cycled without fish or cloned or seeded from existing tanks.

There are lots of threads here to talk you through the process of fishlessly cycling a new tank with ammonia, frozen prawns (shrimp) or a proprietary product and making your tank a nice place for fish to live.

All well and good if someone informs you of fishless cycling before you get fish.
Google fishless cycling and pages of links will appear but few books mention it & fewer shops will tell customers of this option.

This means that unfortunately tanks end up being cycled with fish present. Sad

To hopefully give these fish a reasonable chance of surviving, with as little stress as possible, you have to have a very basic chemistry lesson.

The process is called cycling because the breakdown of fish wastes to a safer form is known as the nitrogen cycle or nitrification cycle.
The toxic ammonia that fish excrete is turned into (still toxic) Nitrite by bacteria. Different bacteria convert this Nitrite to Nitrate which is far less deadly.
Typically Ammonia levels rise to a peak and then the Nitrites start to appear. Ammonia levels fall followed by an often sudden drop in Nitrites.
Nitrates will start to climb after the Nitrites appear.
When Ammonia & Nitrites reach zero and Nitrates rise the tank is cycled. The whole process can take several weeks or even months if fish are present.
In a fishless cycle the ammonia, which is bacteria food, can be raised to a level where any fish would quickly die but a lot of bacteria develop comparatively quickly. With fish present there is less food for the bacteria so the colony takes longer to develop.

A planned fish cycle, back in the days before fishless cycling was known, would involve a few, (no more than a fifth of the tank’s capacity) hardy fish, (generally platies, goldfish, or danios) and lots of water changes. The only expense was lots of dechlorinator and replacement fish when fish died.

Unfortunately we are hearing of more & more cases where people are sold a full stock of fish for new tanks & a bottle of maturation fluid ( for which I have seen no real proof of effectiveness) and they find forums when fish start looking ill and they seek help. Then there are tanks where the filter bacteria gets killed off. This may be from medication or chlorine in tapwater or a change in filtration.

In this situation these are possible options which can be used together :-

Acquire some mature filter media from a healthy tank. This is often the best & least stressful way as it introduces live bacteria of the correct species and they can get straight to work. Even some tank water that has had a mature filter’s sponge rinsed in it will carry some bacteria to seed the new filter. Gravel from a tank with an undergravel filter is a less effective option. these may appear dirty & smelly but it need treating just as you would a live fish and carefully adding to your tank or filter.
Don't rinse them.

Take back any less hardy fish to the shop. Often difficult, especially when children have named them all, but delicate fish will probably die when the nitrite spike occurs. If you are unsure which fish are hardy just ask.

Consider a larger tank immediately as the dilution of wastes with lower stocking levels for the size of tank gives the fish a better chance of survival.

Add plants. If the tank has any lighting add bunches of Egeria/Elodia (the tropical version of goldfish weed) or duckweed. These will use the fish wastes.

Start a regime of daily water changes. The replacement water needs dechlorinating and temperature matching to the tank before adding it. Between 10% & 25% may be needed and this amount can be decided by testing. If in doubt, change more water.

Purchase test kits. It generally works out cheaper to buy a mini master kit, which will have Ammonia, Nitrite, Nitrate & pH tests, than individual kits. The dip strip kits are not very accurate & liquid ones are far more reliable as well as cheaper to use.
Without test kits you could need to do daily water changes for months. With the kits you will be able to tell how the cycle is proceeding and gauge when water changes are necessary. The only safe levels for ammonia & Nitrites are zero and this is the aim at the end of the cycle. The time to do a water change is when the levels creep towards the second level on the test kit's colour chart.
Nitrates need keeping below 25ppm. Although these are less toxic and can be allowed to rise a little higher in a cycled tank, any additional stress on the fish is best avoided.

There are products which can remove ammonia, nitrites or nitrates but they are for emergency use only as you will still have an uncycled tank.
Some additives can interfere with test results and cause confusion.
Some products sound too good to be true - they usually are.
In the USA you can purchase a product called Biospira which is refrigerated filter bacteria. It is worth trying but its effectiveness can be compromised by how it was transported & stored prior to purchase. Keep testing, just in case.

Watch your fish. If you see any signs of lethargy, colour changes, hanging from the surface, rapid breathing, mouth opening and closing or redness of the gills don’t wait but do a water change with prepared water immediately.

Don't despair, lots of people and fish have been in the same situation.
We know that by coming here you want the best for your fish and so do we.
Do have a read of other topics and if you have any questions just ask.
_________________
Sue

First bred tetras in the 1960's, Discus 1970's, more recently bred cichlids, L no. plecs, catfish, characins & cyprinids. Community, biotope & breeding tanks. Trying to keep on top of new developments in products & techniques.