Mysterious deaths in well established 300 Gallon tank

[Abhishek Bonnerjee]

Good day All,
I hope this is the right forum to post this...I really need help please, I have a 300 gallon box shaped custom built tank 7 ft x 2.5 ft x 2.5 ft, housing one 21 inches Silver Arowana, 5 Kois each 3-4 inches, One Sevrum (Now dead without reason) which grew upto 6 invhes for the last 10 months, 3 angels of upto 3 inches in size, 4 blood red parrots each more than one year old and 3-4 inches in size, and two juvenile Albino catfish also well settled in the community for more than 6 months now. I had two Sevrums raised for last 10 months out of which one fine day one of them died suddenly one morning, and yesterday now my other sevrum is gone found dead in the morning today, without any reason (or reason m yet to identify). I change water every week and I have a strong external filter equivalent of fluval, sometimes I do water changes in two weeks ...All of the fish are staying happily and growing rapidly for the last 10-12 months now suddenly in a span of 3 months both my sevrums died one fine morning. I have two 450 watt heaters maintaining tank temperature at 28 Deg C. But I do not as a practice measure parameters of the tank. I also use dechlorinator on every water change as an additive and also little bit of prevention medicines during water changes. I feed them Azoo aro sticks all of them once a day sometimes keep changing with Hikari dry. Kindly advise if I am doing anything wrong..I know checking water parameters should have been done which I just got a kit for testing the water. But other than this for 10 months I never faced any other problem.

 

[predatorkeeper87]

Well. get us the water parameters. Right off the bat I see a few things wrong. Water changes should be done weekly. what exactly is your filter? is that the ONLY filter you have on the tank? Why are you using meds during a water change?

 

[predatorkeeper87]

Looking at the picture that appears to be the only filter you have. I'm going to guess your parameters are out of whack. There aren't a ton of fish in there but without maybe enough biofilter capacity you may be looking at a minicycle here.

 

[smitty03281964]

I agree with some of what Josh is saying. Which is why are you using medicines when doing water changes. I don't think doing your water change every 14 days is the problem unless you are overfeeding and allowing the water to become very foul. Are you cleaning the filter when you do the water change. If so you could be removing to much of the bio set up which could cause nitrates to spike.

 

[predatorkeeper87]

I agree with some of what Josh is saying. Which is why are you using medicines when doing water changes. I don't think doing your water change every 14 days is the problem unless you are overfeeding and allowing the water to become very foul. Are you cleaning the filter when you do the water change. If so you could be removing to much of the bio set up which could cause nitrates to spike.

my only concern on the water change was the low filtration on the tank. one filter jams fast when its the only mech in the tank.

as for the medicating during every water change, that's asking to create a superbug resistant to your medication.

 

[smitty03281964]

A Abhishek Bonnerjee You also said you have a Fluval. Fluval make many filters which one do you have?

 

[skjl47]

Hello; Looking at the picture, it appears that the lights are under the glass cover. If this is so then it follows that there will be high humidity and condensation under the cover. This humidity can affect lights. In the distant past I ran tanks with lights exposed to the water. I had issues and no longer do this. I now make sure there is a barrier between the water and my lights.

 

[Woefulrelic]

I'm of the opinion that koi don't do well in a tropical setting and that your going to risk your aro or koi stressing because there's no happy medium temp. I would sell the koi or put them in a pond because they are on the fast track to becoming feeders. I would also find a proper cichlid pellet if you intend to raise them, cichlids and especially severum need a varied diet and they are quite partial to veggies too. That high protein diet would likely lead to hith which can kill it, and that might explain why it's the lone sacrifice because it was more prone to hith than your other fish.

The only problem with that theory is that to the best of my knowledge it would be very apparent, and you probably would notice long before the fish died. True to its name hole in the head disease (hith) will manifest as pitting on the face of the severum. Water quality plays a big part of hith as well so if you're going 2 weeks no water change and feeding a protein based diet then you could see this condition deteriorate quickly.

Get in the habit of testing your water so you can diagnose problems and make it very simple to combat quality problems.

 

[Abhishek Bonnerjee]

Hi guys thanks for all your replies and yea I am very much able to relate to what you are saying, water change once every 14 days and sometimes once a week, parameters not monitored was a mistake...I will elaborate a few vocabulary errors I made above
I add "ridall general aid" and antichlorine, not medicies, during every water change, food is very disciplined and limited always once a day just enough for them to eat in 10 min, no leftovers allowed, however just before the Sevrum died the last two days feeds was a tad bit above normal since the Arowana was behaving a lil more hungry than usual so my wife fed them twice for the two previous days before the sevrum's death but it wasnt so much extra to cause really a prob, or maybe What didnt look too much to me was really more to cause this. Today water was changed again, with antichlorine and ridall gen aid. My point is this same practice I follow for last 10 months and none of then get affected by little variations so much. Yes Filter capacity may be a problem for this amount of water its almost 1 cubic metrea of volume (990litres), and no I dont clean filter with every water change, filter media replaced once a month. I wil let you guys know as soon as I measure the water parameters. Also there was an atmospheric temperature drop at our place as winter is setting in, I live in Goa, India its temperate climate but that again shouldnt have been a problem since i have the thermostats in place.

 

[Abhishek Bonnerjee]

Okay

Hello; Looking at the picture, it appears that the lights are under the glass cover. If this is so then it follows that there will be high humidity and condensation under the cover. This humidity can affect lights. In the distant past I ran tanks with lights exposed to the water. I had issues and no longer do this. I now make sure there is a barrier between the water and my lights.

I agree on this but see my tank is a custom built with glass tops as well, all the glass are 12 mm in thickness and its really dificult to fit something else, do let me know if there is any other solution to this?