Do bacteria multiply as fish get bigger?

[HoundsNTrout]

Wasn't sure where to post this. I have been raising trout to 4-6" the past couple years in a couple 300G totes in a RAS system. No real issues. Had a few lesson's learned but for the most part I have had minimal loss and all healthy fish for stocking purposes. 90% probably. I input 50G of fresh water daily and use chiller ( stand up freezer ) in summer and heater on timer in winter to keep water at a constant 55 to 58F temp.


Anyway. So, the tank is cycled to take care of 8ppm of ammonia and 2-3 ppm of Nitrites in less than 12 hours.
Question. Since the tank is cycled to withstand or take care of that large amount, what happens if very tiny fry only produce not even say a tenth of that every day until of course they start growing ?

Will the bacteria slow down to meet the demand and then start growing again? Or will they die off?

The reason I ask is I know ( based on tests I did ) that 1500 fish at 4 inches long in my tanks will produce close to 6-8ppm ammonia over night with regular feeding. And at least 8ppm with more feedings when I am trying to fatten them up before they get stocked.

So that is why I have been cycling tanks to take a huge amount of ammonia and nitrites.

Will the bacteria die off if my eyed eggs or tiny sac fry are not producing enough ammonia?

OR should I cycle the tank to only take care of say 1ppm and then as the fish grow the bacteria grows in numbers to meet the demands? Is that how is works? OR SHOULD work?


In my tanks the fish usually grow 1" per Month or more at a temp of 58F.

Another thing I was thinking that might be off kilter here or not good idea: What if I were to put a dose of ammonia in the tank every day to get it up to 2 to 4ppm but also add Prime? Or say every other day or every 3rd day? Probably stupid eh? lol

The college hatchery where I get eyed eggs and fish is a RAS system as well, much like my set up where they cycle in new fresh water at a very low rate. Mine is 50Gallons per day in a 300G tank. ANd mostly to keep the Ph where I want it.
The hatchery has HUGE bio filters but they also raise fish to certain sizes in different sized tanks before changing tanks so I think the filters go hand in hand with each tank.


Thanks for any insight.

 

[ShanerBock888]

As long as you have enough biological media to house the proper amount of bacteria they should multiply in number to fit the bioload. If there's not enough ammonia being produced to feed the current biofilter, the bacteria population will thin out to fit their food source, but will also grow to fit their increasing food source. I use Blue Ribbon ammonia (or any brand that's 100% ammonia with no additives or scents) for fishless cycles but would not recommend adding ammonia with fish already in a cycled tank. Since the biofilter levels itself out to fit the amount of ammonia available, the current biofilter might not be able to handle this sudden increase in ammonia, and your fish will have to live with unhealthy ammonia levels until the biofilter catches up.

 

[HoundsNTrout]

Awesome, thanks. I have tons of media in both the bio filter and on bottom of tank. I use 1 Gallon jugs with drilled holes and fill them with gravel. That way makes it a lot easier to suck up all the crap every night without disturbing the media and bacteria.

How long would it take for bacteria to die off if there was no ammonia? As in I don't know for sure if eyed eggs release any ammonia. I wouldnt think they do. I usually have eggs in small tank for a week or so then it takes maybe 2 1/2 weeks after that they start eating.

Maybe I should put a shrimp or two in the tank until first feeding to keep the bio filters happy?
That was another question all together I guess. lol

I did have a problem once and couldn't figure it out. Bio working great, put the eggs in, hatched. Started feeding them and one morning saw ammonia and nitrites developed to like 1ppm and was like WTF?

I bet they died off while the eggs were incubating. But not certain.

Does that make any sense?

 

[pops]

what makes more sense is un eaten food, BB is very hardy and will go dormant for long periods with out ammonia/food. fry do not eat allot so you have allot of free floating organic (fish food) suspended in the water, this more than likely caused the spike. the cycle should have picked back in a few days, being trout I am thinking cold water, BB responds slower in cold water and takes longer to cultivate, still once established and thriving should have no problems keeping up with the fish as long as the bio filtration media space is there.

 

[HoundsNTrout]

quote " being trout I am thinking cold water, BB responds slower in cold water and takes longer to cultivate " ..

LOL. You got THAT RIGHT. It's pretty insane at 50 degrees. I've learned to seed now which really speeds it up a LOT. Even seeding from my 55G to the 300's saves a month.

Thanks a lot pops, that makes sense. So I'll just keep adding enough ammonia to keep it happy until I place the eyed eggs in and then just go on assumption the dormancy will come out as soon as ammonia starts appearing. In my case normally a month from the time the eggs are in the tank and they start eating.

 

[HoundsNTrout]

Quick videos of a tank. Sorry for the narrow frame. I can't figure out how to get it to full screen. Maybe someone here knows. Its on my droid phone. IDK, anyway heres my set up for trout tank. My next little thing is ( since this is called MonsterFishKeepers ) I want to see how big a couple fish would grow in a tank like this in 2 years time under same conditions.