Backyard Aquaponics
A place to discuss aquaponics

Ok simple question...How many times should you feed your fish a day and should you feed them everyday? I ask because I have heard to skip a day of feeding but my fish seem very agitated if they don't eat twice a day everyday....

I don't know if there is a right way or not but I'll tell you what I do.

My fish 40 x100mm comets live in a system of 1800 liters or so about 400 liters of tank 700 liters of wet media in the grow beds and 700 liters in the sump my system is about five weeks old fully cycled with excellent growth and water parameters of PH 7.4 Ammonia 0.0 nitrite 0.0 and trace levels of nitrates I have my tank salted to 2ppt

/bragging off

Man......I feed my fish nearly every time I go past em, can't help it. Not much mind....maybe 2 or 3 thick pinches of 1.5 mm floating pellets in the morning and one light pinch 2 or 3 times through the day probably another couple of thick pinches just before it gets dark.

My fish are fat and happy they see me at the tank and come up for a feed, all jostling each other to get the best spot. It's great. I just love it. They eat everything all at once and then they go and hide under the SLO pipe while they fart and burp out any excess air they got while eating then come and play around my hands and brush against my fingers as I swirl up the tank to move any excess solids towards the SLO.

If you are observant you will find what your fish seem to like and what is natural for them. I think you can trust them to not over eat too much but, all the same, you should scoop out any excess food that may be left after the feeding frenzies during the day.

Finally if you start having water quality issues and the fish have previously been healthy you may want to slow the fun.
Remember you can cut off their food for as long as a week and the fish will not suffer too much. This would be very common if they were living wild.

Enjoy your fish they are the best thing about AP they are just so interesting.

If you plan on eating your fish you may not want to get too fond of them but these fish are my pets. In the future I will have eating fish that I will care for but not let myself become fond of.
It's hard at the top of the food chain

It depends on species climate and a whole bunch of other variables but the main thing is what is your objective.

The two extremes are:

trout in water of around 18c where you have a well established system matched with an experienced APer who wants them to grow as fast as possible and produce as much nutrients as possible so they can feed them as much as they will eat as many times per day as they can without overloading your filtration capacity.

vs.

Silver perch in winter where they just won't eat so don't feed them and you just want the system to tick over until it warms up.

After looking at Stuart's post I may not have been that helpful so consider the following

The ability of a system to convert ammonia through to nitrate and then be removed from the system water by the plants and so keeping our fish healthy really depends upon two biological processes that occur within an aquaponics system and the two biological function both become more or less efficient under certain conditions.

The first biologically significant process is the conversion of the ammonia/fish wastes into first nitrites and then into nitrates.

Lets deal with the second first:

The second and easiest for us to understand and deal with is the removal of those nitrates from the system by the vegetation planted in the garden beds. In the case of the plants, as long as there are enough plants in the system and conditions are suitable for vegetative growth then final removal of the nitrate from the system will occur without too much intervention on our part.

The first is a function of the bacteria in our systems and they in turn are effected by several factors.

The first is available surface area for the bacteria to populate and the other main factor is temperature. Whilst there are other factors such as water PH and the food needs of the bacterias that will effect them the bacteria will eventually evolve colonies that will be adapted to the prevailing environmental conditions as long as they have sufficient surface area to populate.

So, back to surface area.

If we have a given surface area then we can estimate how much fish waste per square meter per day that the bacteria in that surface area can process into useable plant food. within a given period of time. This idea is all that we will be able to deal with at this time because each media that the bacteria populates has a different surface area for a given volume.

There are some medias that have a known surface area.... K1 being just one example. As we know this surface area we are able to know how much food we can put through the fish and have the bacteria on this media do their job.

As an example to help us visualize these ideas let pretend we have 100 ltrs if K1 media in a suitable bio-reactor then we could probably feed our fish 250 gms of 35% protien fish food per day, fed to the fish in one portion once daily. If we spread the feeding over a two portions we can feed, perhaps, 10% more and if three, perhaps, 20% more these are in no way real numbers but only given to help us grasp these concepts.

I hope this helps more than me blurting out about how much I enjoy my fish and goes some way to explaining why and how I get away with treating them as I do

While the information Telonline has offered is true using it to design AP systems is more than dangerous for newbies. In fact it is a recipe for disaster.

It's also likely to be a bit of a waste of time even if you are going to a system where you remove all the solids.

The filtering function discussed above is bio-filtration only. In AP systems it is only a concern during the commissioning of a new system as the bacterial colonies become established. In aquaculture it is important to appropriately design and size bio-filters because they can be a significant part of the construction cost and building them bigger than they need to be costs capital and can increase operational costs.

In AP your maximum capacity is your maximum feeding rate whether that feed be given to 10 trout or 20 silver perch (two extremes). What limits you feeding more is your systems ability to process the solids. The reason for this is even in systems without gravel or other media (where the solids are removed) there is generally enough surface area in the hydroponic components to take care of the bio-filtration function. Especially once the roots get growing although you can get yourself into trouble if you were to harvest all your plants at once because you would remove all the surface area of the plant roots at the same time (that would be bad).

In most AP systems and in all cases (that I know of and can conceive) that use gravel the bio-filtration function of the system is absolutely massive. Therefore we don't need to worry about calculating it. The ability of the system to handle solids on the other hand is another matter and most system have problems with their fish because they over feed relative to their systems ability to process the resulting solid waste.

This tendency and the resulting fish mass deaths has led to a number of AP advocates to state that for this reason it is essential to add solids removing components to AP systems. While that can fix the problem it also makes the systems more complicated whereas feeding less or adding another GB would also work just as well or better.

what they said
It's better to feed more frequently than with big meals.
Morning and night is fine
Trout are hungry all the time.
The calculations are important when your fish get bigger.

Not so much for bio-filtration though.

If you do the calculation for gravel @ 200m2/m3 then you could feed close to 1.5kg of feed per day with only 1m3 of gravel.

Based on the 2:1 rule you would have a 500L FT to go with 1m3 of gravel. Even feeding @ a rate of 6% of body mass per day that would be 26kg of fish in 500L or a stocking density of 32kg/m3.

Since most people stock less than 30kg/m3 (even just before harvest) and feed at rates closer to 3% of body weight per day or less you can see that the bio-filtration of systems is way more than it needs to be.

In the universe that is AP, I would follow Stuarts advice over mine.... any day.

I think.

It should be noted I do have a mongrelized Chop 2 system with solids removal and a bio-filter, of sorts, directly off the fish tank and no solids make it to the grow beds.

Thanks T.

Back to the original question it really does depend on what you are trying to achieve but feeding more times per day is only necessary if you are pushing your fish/system hard which almost all of us are not (except the solids removal guys who also are not because they are removing the solids).

Your fish, especially trout, will get grumpy if you don't feed them but not feeding them will not harm them. In the wild fish often live from feast to feast with large fasts in between because they are poikilotherms (cold blooded). While not feeding them will not harm them they may harm each other because hungry grumpy fish can be aggressive towards each other.

Spreading the feed across the surface of the tank rather than dumping it in one spot can help stop the fish fighting for food.

I don't want to push the system I want to raise lettuce more then raise fish. I know the fish get grumpy when hungry. It's hard not to over feed especially when you start to care so much for these little guys. do you think its ok to feed 2 times daily in the morning and at night for 20-30 minutes each time adding a little at a time if they eat it all up? they seem to eat less in the morning but seem pretty hungry at night time can I feed them everyday? do you skip days of feeding?

i feed 2x a day.. but have been way from the system for a weekend here and there..
don't feed by time, feed by volume.. small fish will eat 5% up to 15% of their body weight daily, adult fish get 2-4% of their body weight daily, break it up into whatever number of times a day work for you, but if the fish aren't eating the food within 15 minutes or so, remove the uneaten food, or you'll have solids build up that you don't need
need to weigh a few fish?.. put a bucket of water on your scale, note the weight, then add 4 or 5 fish (depending on size) to get an average

As Keith said its not the time or frequency of feeds but the amount.

When I go away for a weekend the fish don't get fed.

When I've got stuff on during the day they might get fed twice a day but as we go into winter there will be times when I will have to leave before sunup or get back after dark which means one or no feeds on those days.

When I'm working from home I after go down to the greenhouse three, four, six times a day and the fish get fed every time. On such days they get fed more whereas on a dya were they get fed only once they are not able to eat their daily ration in one sitting so they get less.

As long as my fish are eating I don't have to worry about over feeding them because my GBs are so large.

To my mind, that sounds like a good way to feed them if you can only get to the tank twice a day.

You absolutely can miss the days feeding and it might actually be good for them by allowing them to reduce or turn over some fat reserves.

I don't know how often you do water tests (I'm presently testing every two days.) but I would stop feeding if water parameters got a bit out of optimal or I noticed some flashing, rolling, inverted swimming or other odd behaviors. I'd remove the effected fish and only resume feeding when I was satisfied the fish were safe.

I guess some fish could eat till the point of danger to themselves. I mean....you can't fight Darwin and if they remove themselves from the gene pool it might be a good thing.

I've noticed my fish feed in surges, they will attack the food then settle down under the SLO pipe for a couple of minutes then surge again. I don't like to see uneaten food as I'm leaving the tank area so I either stop feeding them early and leave while they are still smacking their lips at the surface or I scoop any uneaten food and go back inside.

I don't think you need a lot of fish food to drive the vegetable side of AP but Stuart might know a good ratio of fish to greens.

Have you said what species of fish you have or are planning to have?

As far as I know the only systems that have good pubished data on ratios of fish feed to plant production are the UVI system and its copies. Some of these systems reintroduce solids after mineralisation but the published details on their method are a bit thin.

You dont need many fish at all to grow a lot of vegies. My two bigger systems have silver perch and catfish in them and both will stop eating soon. So I am getting 20 trout to put 10 in each system for the winter and this will power the vegies along just fine
And yes you can put trout in with silver perch and catfish with no dramas