My fish won't grow!

Hi Folks,
wondering if anyone had an opinion on this - my fish aren't growing to full size and/or are very slow.

I do 25% water changes per week and all tanks are understocked / overfiltered, and I use polyfilter to soak up any excesses or mistakes (plus putting JBL Clearmec-plus in all externals)

All water parameter are fine - never any nitrate/nitrites/ammonia.

Could I be too overcautious in feeding? Due to work - I only get to feed in the evenings and all tanks get 2 feeds over the course of 5 or 6 hours. Food is a random mix of various flakes, pellets, wafers, wet-frozen bloodworm, daphnia and recently live brineshrimp.

Never had this problem before (20 years ago!) but can't spot what I'm doing wrong this time

Thanks,

Jim

Hey Jim; what fishes are they?

could be stocking levels even with overfiltering if the fish dont have the room to grow they could stunt, otherwise maybe they arent getting enough to eat even with 2 feeds, try adding a 3rd small feed or potentially it could be the food your feeding them hasnt the right nutrients for them and a change may do the trick........ what is the tank volume and how many fish of what type are in it... this might help us find a solution to your problem

Things that stunt or retard growth:
unbalanced diet;
not enough food (the amount depends upon fish)....but that means increasing biological filtration efficiency;
growth inhibitors;
dominant fish;
over-crowding;
self-inhibition of growth (water changes help that);
excess energy being wasted to detoxify, or to rid the body of various waste products, or in attempting to fight imbalances of water chemistry;
excess energy being wasted for shoaling fish not being in a big enough shoal to swim in a slip-stream (!!);
illness (including liver or kidney degeneration);
poor genetic stock; and
stunted at an early age....and, as such, will never reach full size.

Also, speed of growth is species dependent. Some may rapidly reach 50% full size and then take ages to get any bigger; others will evenly grow up to a certain size and then

As questioned in an above post.....which fish?

ian

JohnH wrote:

And - this is really significant - frozen foods, there seems to be very little nutritional value in them (something I wasn't fully aware of until I spoke to Kealan about the subject) and even your 'prepared' (for want of a better description) foods.
If (and it's merely a suggestion here) they are at or even reaching their 'best before' date the nutritional value drops really significantly.
All those sorts of foods - once opened - really do need refrigerating to help slow the degradation process.

Just a couple of thoughts.

John

Was just curious about the bit I have highlighted in bold John. Could you elaborate more? I assumed it was like the Birdseye Frozen Peas - that freezing keeps all the nutrients & goodness in?

Still no reply back from Jim?

@Pheromones (or similar).....I wasn't go to go into much depth on that, but just to note chemical signals from one fish to another seem to have an effect, and that that effect depends upon species and may even have a 'stunting' effect on the individual producing such chemicals.
But that is another complex system of behaviour vs physiological/biochemical systems.

We really note in the livebearing tooth carps (guppies) a profound 'dominant' large fish effect.

But, domination also has other effects on fish size.

@Frozen food........JohnH made a very important point.
Growth is not just about the bulk of food given, or the total protein, or total vitamins etc. It is about having the correct balance of nutrients and the right quality of protein.

Certain vitamins and chemicals are quite heat labile (don't last long under warm conditions). But there are some that actually are more stable at room temp than they are if frozen (oh, if nature followed the rules of Birds Eye!!).
Those compounds that are not stable to low temps will decompose on freezing, and those not stable at higher temperatures will degrade on defrosting. But most are stable.

Also, constant freezing, defrosting, freezing etc will eventually burst cells in the food....and 'goodness' will be available in the water (of which the fish will probably not eat !)

Another point is that food may not be 'gut-loaded' with the appropriate things.....and thus some foods maybe no more than 'fibre'.

Now, that is not to say there is anything wrong with frozen food.....but a balanced varied diet is essential.

Also....dried food....same problem. I tend to buy smaller tubs of food as once opened many chemicals will oxidise and become a waste.

Another point that is often missed is the amount of protein.....but it is the quality of the protein that is important.
In order to grow, a fish must lay down connective tissue (amongst other things), but to do that you need to have a supply of amino acids for the connective tissue. Hydroxyproline (an amino acid) is quite important here....and if there is little of it in the diet, then there is deficit in the source for building connective tissue. Now the body can make certain amino acids certain other amino acids....but that takes energy, and will again compromise growth if the required amino acid is lacking in the diet (yep...that bit gets complex as well).

@Jim....where are you..what fish etc do you have?

ian

I was going to say Jims reply has been stunted, but reading his post I reckon he wasn't home from work yet ?

hi jim, as causes for poor growth rate, we could add inbreeding, incorrect feeding, too high temperature leading to low oxygen and less active filters plus internal parasites, bullying and stress related low immune system. the last three will even cause the fish to shrink a bit rather than growing.
if the fish are healthy and from good stock then regular water changes and correct feeding for species should lead to good strong growth rates.
as you are an experienced fishkeeper the most likely causes might be parasites or inbred stock imho.
what species are you noticing the problem with? are they wildcaught?

Hi folks,
Thanks for the many responses – and thanks JustinK for noticing why I can’t log on until around now!!

In answer to various questions:

All sort of fish – tetras, barbs, loaches, L-numbers, cichlids, mollies, guppies, platys.

Stocking levels – worst tank is a 260l with about 30 small tetras, 4 clown loaches and 3 L205s, filtration from a Fluval 305. Another, for example, has 9 Odessa barbs, 4 hymenophysa loaches and 1 aymonieri – 240l with a tetratec ex900 and Juwel corner filter.

I was aware of the pheremones / hormones issue, so didn’t try to rely on nitrate reducing resins or organic aqua or anything – but have kept 25% water changes (just ask Seahorse how much RO I buy all the time!!)

I didn’t realise that the frozen food wasn’t so good – I always thought it was less processed than flakes etc . In terms of other foods – I use Sera & Tetra flakes, Tetraprima mini-granules, TetraPro Vegetable flakes, JBL novo granomix, Tetratabimin, various wafer etc etc. All the fish get a bit of everything – different brands etc.

I wonder if maybe 25% water change isn’t enough where certain fish are involved. The tanks most effected contain clown loaches and hymenophysa. In each case, 2 of the loaches have grown to more than twice the size of the others. I assumed this was about food competition, so I fed at both end of the tank at once to give everyone a chance. But I wonder if this genus has a particularly strong “dominance effect” – especially when growing? Either way, given the mostly low stocking, good external filtration, reasonable water changes and clear water tests – I couldn’t see water quality being the issue.

Thanks again for all the inputs – there’s certainly a few things here I didn’t know and other pointers to give me pause for thought

Kind Regards,

Jim.

derek wrote:

hi jim, as causes for poor growth rate, we could add inbreeding, incorrect feeding, too high temperature leading to low oxygen and less active filters plus internal parasites, bullying and stress related low immune system. the last three will even cause the fish to shrink a bit rather than growing.
if the fish are healthy and from good stock then regular water changes and correct feeding for species should lead to good strong growth rates.
as you are an experienced fishkeeper the most likely causes might be parasites or inbred stock imho.
what species are you noticing the problem with? are they wildcaught?

Hi Derek - just noticed this now! Inbreeding could be the case with many of the tetras - who knows where they come from half the time and perhaps inbreeding is an issue with many of the commercially raised species - but I guess I'm buying the from the same shops as everynoe else! Having watched the tanks, there's no real signs of bullying - only occasional sparring & display but nothing sustained.

There are wildcaught fish in all the tanks - so I guess parasites could be an issue. I hadnt really considered it

THe most surprised possibility is high temps - I never thought of that. The temp in the fishroom might very well peak sometimes - I'll actually keep a closer eye on that now that you mention it.

Thanks again,

Jim.

Welcome back Jim; and as you said I learnt a few things myself from your post. Many good tips here indeed.

Jim wrote:

derek wrote:

hi jim, as causes for poor growth rate, we could add inbreeding, incorrect feeding, too high temperature leading to low oxygen and less active filters plus internal parasites, bullying and stress related low immune system. the last three will even cause the fish to shrink a bit rather than growing.
if the fish are healthy and from good stock then regular water changes and correct feeding for species should lead to good strong growth rates.
as you are an experienced fishkeeper the most likely causes might be parasites or inbred stock imho.
what species are you noticing the problem with? are they wildcaught?

Hi Derek - just noticed this now! Inbreeding could be the case with many of the tetras - who knows where they come from half the time and perhaps inbreeding is an issue with many of the commercially raised species - but I guess I'm buying the from the same shops as everynoe else! Having watched the tanks, there's no real signs of bullying - only occasional sparring & display but nothing sustained.

There are wildcaught fish in all the tanks - so I guess parasites could be an issue. I hadnt really considered it

THe most surprised possibility is high temps - I never thought of that. The temp in the fishroom might very well peak sometimes - I'll actually keep a closer eye on that now that you mention it.

Thanks again,

Jim.

Unless the water is so poorly oxygenated that the fish will be gasping, the level of available oxygen in the water at increasing temperatures will have very little negative effective on fish growth.

There is a critical level of oxygen demanded for the aerobic growth relationship, but that critical level is quite low in comparison to the aerobic level required for normal biochemical function.

In general, and unless the upper lethal temperature for a fish is approached, increasing the temperature would tend to increase growth rate.
The decrease in oxygen at higher temperatures is not a rate limiting step (unless, as said, the level is so low that it below critical).

So high temperatures are not, in themselves, a reason for retarted growth.

I'm off for coffee now....but maybe I'll be back to discuss the specifics of your loaches (a shoaling fish).

ian

[quote="igmillichip"
Unless the water is so poorly oxygenated that the fish will be gasping, the level of available oxygen in the water at increasing temperatures will have very little negative effective on fish growth.

There is a critical level of oxygen demanded for the aerobic growth relationship, but that critical level is quite low in comparison to the aerobic level required for normal biochemical function.

In general, and unless the upper lethal temperature for a fish is approached, increasing the temperature would tend to increase growth rate.
The decrease in oxygen at higher temperatures is not a rate limiting step (unless, as said, the level is so low that it below critical).

So high temperatures are not, in themselves, a reason for retarted growth.

I'm off for coffee now....but maybe I'll be back to discuss the specifics of your loaches (a shoaling fish).

ian[/quote]

when any problem with fish or plants arises it is good practice to check all water parameters esp temperature (as too high temps due to sticking heaters etc. is probably the single biggest cause of sick and dying livestock ) so i stand by the statement that too high temps and lowered oxygen levels can lead to problems for many species, including poor growth (as a sympthon)in fish.
debate is welcome but high handed dismissal of others advice is not.