New Tank, Should I Add A Fish With The Plants?


Hello, All. First post here, which is a couple of questions.

I set up a 15 gal. Fluval Flex this afternoon, with 3" of Eco-Complete. All looks good just now and I want to add plants.

My questions are:

1. Should I add a fish to the tank along with the plants, so that at least a little ammonia will be generated, or should I wait several weeks before doing so.

2. Should the answer to #1 be "no fish," then should I add something to fertilize the tank? Or is the Eco-Complete enough at this stage?

I"ll be driving an hour to That Fish Place for the plants, and I want to know if I need to get a small fish or two (perhaps cherry barbs or zebra danios) to initiate cycling.

By the way, I was really impressed that there was *no* water cloudiness from the Eco-Complete. I was careful not to disturb it as I added the water.


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Why do you want ammonia?
Is the tank cycled?
What fish are you adding in there?

Jocelyn Adelman

Yes the tank will need to be cycled. This can be done without fish (dosing ammonia) or with fish (done, but not usually recommended)
So... how do you want to cycle your tank?

Second is what ferts are you thinking of adding? The faster the growth the more ferts needed. Available types are liquids or powders you mix on your own (cheaper). Liquids can be broken down into separate macro/micro or "all in ones". Then there are root tabs for root feeders (swords, crypt wendtii.... even wisteria appreciates them but not 100% necessary for wisteria. Even with eco complete you should use root tabs for root feeders.

I usually plant my tanks while cycling (however I use seeded media so it's pretty quick). I dose ammonia until day before fish are added. Cycling without seeded media can take 4-6 weeks.
Depending on what plants I have used depends on what ferts I start with and when. All my tanks receive potassium by the third day, full ferts by the following week... I like to give a few days adjustment time, especially in new water- will have trace minerals present, plus the ammonia from cycling. I try to avoid any algae issues that would require a water change while cycling....
The plants will need ferts soon, the eco complete isn't enough.

(Love eco complete!)


Got it. I'll take care of the plants immediately -- planted some today. I also bought some of the root tabs for the rooted plants -- Java fern, 2 species of swords, Anubias and Glossostigma elatinoides. I also got a bunch of Egeria najas (which will mostly float?). We'll see how the growth goes.

As for cycling, I'll think a while about it, but at the moment I am leaning toward using a fish or two. I have another established tank that can serve as a refugium if (when?) ammonia spikes and the fish look uncomfortable.

It looks like the chemical cycling agents folks use are all glutaraldehyde-based. I have decades of experience with that stuff in my laboratory. I'm a retired developmental biologist who worked extensively with fish embryos -- Perca, Catostomus, Oncorhynchus, Oryzias, Danio, Lepisosteus and others. A major rule that I kept in my lab is that anything that ever came in to contact with glutaraldehyde would never again come into contact with a fish embryo that I wanted to keep alive. It makes me uncomfortable to bring it into my home.

Now that I blathered on about glutaraldehyde and hit the post button, I slapped my forehead. Glut would be for plants, wouldn't it? Cycling for fish would be ammonia. <sheepish grin>


If you have an established tank, there is no need for you to cycle a tank. Stick the filter cartridge from the new filter in the filter of the established tank right next to its cartridge. In two weeks it will be able to run your tank. (I check for ammonia spikes anyway, but my last 6 tanks were instant cycles because I always keep extra media in all my filters. I hate cycling)


I'll do that. The simplest solutions are always the best. Hats off to you, KImberlyG.


You are welcome. Like I said, I HATE cycling.

Jocelyn Adelman

Also you can add some media from the old filter to the new filter (seeded media)

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