RTC growth slowed down drastically after 1st year

[Jamal Haidar]

Hi, I have 2 RTC that I obtained on Nov. 2013 both were 4'' in size. In the first year their growth was very fast but it slowed down now or actually nearly stopped. Their sizes are roughly 14'' & 16'' now. I feed 3 times a week with white fish fillet and frozen shrimps and sinkingpellets.

Tank size is 180 gallons but soon I will transfer them to 550 gallon tank. Water conditions:
Temp 26° C
NH3 = 0 ppm
NO2 = 0 ppm
NO3 = 40 ppm
PH = 7





Is there any recipe for faster growth?

 

[thebiggerthebetter]

Welcome to MFK, friend!

What test kit do you use?

Yeah, from the first photo I can see that they have body proportions of ~2 year old RTC but they are short having the body length of ~6-10 month old RTC. Agree with Dazza, this looks like stunting.

What's your water change regiment? High-ish nitrate tells me you are lagging behind in wc's and this would also be consistent with stunting due to accumulation of hormones in the tank water. That plus the smallish tank would lead to stunted growth.

Is it possible you are underfeeding? 3x a week is the frequency but what's the amount? Are their tummies nice and round after each feeding? Underfeeding could be a factor too. The diet appears ok.

Finally, it may be genes, albeit this would be the first time I've met with this. Short-body RTC are known, which yours are not.

(The thread is split off from here, page 3 http://www.monsterfishkeepers.com/forums/threads/red-tail-catfish-growth-unbelievable.643162/page-3 )

 

[Jamal Haidar]

I use API & JBL test kits. I perform WC twice a week 50% and 30% respectively.
It is possible that I am under feeding as you mentioned. I will increase the amount but I think this will require more frequent WC.

 

[thebiggerthebetter]

Liquid test tube tests?

What are your nitrates in the tap water?

What's aeration like?

Perhaps I was not clear but underfeeding alone would have to be extreme to cause stunting. Yours is not at all. In fact in our hobby it is better to underfeed than to overfeed (when feeding a balanced diet, of course). But coupled with insufficient wc's and too small a tank, I think we just don't know what effect an underfeeding overall or underfeeding a certain nutrient(s) might have.

BTW, are you familiar with the thiminase and its issues?

Anyhow... what I'd focus is on increasing weekly wc's to 75% twice a week at a minimum (more is better - you need to effect a large change to possibly see a significant difference) and getting them asap into a bigger home.

 

[Jamal Haidar]

Nitrate is not detectable in my tap water. In kuwait the only fresh water we get is from sea water desalination.

And aeration is good. I have a sump and the water circulation is around 7 times water volume per hour.

No i am not familiar with the thiminase. But I think increasing the % of WC will help until I transfer them to the new tank. But isn't 75% too much?

 

[thebiggerthebetter]

Aeration is not only about the turnover but about efficiently bringing the oxygen-rich surface water down to the bottom. Also, 7x turnover may be too little IMHO for a 180 gal tank but the tank dimensions matter a lot. What are they?

Unless I have a sensitive fish, my tanks usually get 90% weekly or twice a week. I've not noted any problems. My fish appear to like it.

 

[Jamal Haidar]

Tank dimensions are 150 X 55 X 80 cm (LXWXD). And the sump holds extra 30 gallons.

I have also Santa Monica Algae Scrubber in the sump which help in oxygenating the water


And thanks the bigger the better for your advise

 

[thebiggerthebetter]

I only hope to help.

So the tank's much taller than it is wide. That's unfavorable for aeration as it heavily depends on the water surface to water volume ratio. The higher the ratio, the better the aeration.

I am not familiar with the algae filter. It sounds good but do you know that plants, as all living organisms, consume oxygen in the dark while producing none?

IDK your full stock but what I see are two RTC and a pacu, all relatively large, bulky fish with a high bio-load and biochemical oxygen demand (BOD). Hence, again, I'd focus on
-- perhaps intensifying aeration,
-- increasing wc's by a lot, and
-- getting them into a larger tank asap.

I'd NOT feed them more than you have been for the same reasons.

 

[Jamal Haidar]

The lights are on for the algae scrubber for 22 hrs in the sump. So there is very short dark time.

The algae scrubber also operated by huge air pump to flow the water through the scrubber, aeration supposed to be adequate.

And I totally agree with you more WC is required and I have to move them to a bigger tank soon.

 

[matthewr262]

Nitrate is not detectable in my tap water. In kuwait the only fresh water we get is from sea water desalination.

And aeration is good. I have a sump and the water circulation is around 7 times water volume per hour.

No i am not familiar with the thiminase. But I think increasing the % of WC will help until I transfer them to the new tank. But isn't 75% too much?

Does Kuwait fortify the disilled water? And if they do, the water may be missing key minerals. Using a water mineral supplements wouldn't hurt.