Go down nitrite! Emergency filter problems. Finding the perfect release site. Feeding those bottom dwellers.
Persistently high nitrite
Every year, some schools experience extended periods of elevated ammonia or nitrite. Since these two toxic compounds can be very harmful to our fry, such stretches can be very worrisome, if not tragic. Recently, I've been in regular correspondence with Kathleen Backus and Brendan McKenna, of Village School of North Bennington. On April 10, Kathleen sent me this e-mail.
I forwarded images Kathleen sent me to our TIC experts: Robb Cramer, Chuck Dinkel, and Tara Granke. Robb and Cramer though it looked like the fry had saprolegnia.
On April 16, Kathleen wrote this:
Today our healthy large fish are dying. I pulled out 7 large dead trout today and as I sat there more were dying. It is happening fast.
Here are two weeks worth of VSNB data Kathleen sent me on April 16.
As you can see, ammonia was slightly elevated on 4/2 and then declined, ultimately falling to zero, as nitrite began to rise. Unfortunately, nitrite stayed at 2 ppm or higher for at least the next eight days. I say "at least" because, when Kathleen rechecked the nitrite on 4/17, she found that it was still 2.0 ppm. (When I believed the 4/16 nitrite reading was 1.0, I assumed that the nitrogen cycle was finally coming to its conclusion--as Brendan McKenna put it: "The fever had broken.")
Especially those 3.0 and 4.0 ppm nitrite readings were probably putting a lot of stress on the fish. Eventually (as of today), ten fish died. Here's what they looked like.
Here's Robb Cramer's diagnosis:
Those are high Nitrite numbers. My guess — the high Nitrite numbers led to increased susceptibility to infection and the fish acquired an infection during that time period. That is one of the consequences of poor water quality — immune suppression. So even if it is for a relatively short period of time, when the fish are stressed, they become more susceptible to disease.
Chuck Dinkel, Maryland TIC coordinator, added this:
A product such as Amquel Plus will detoxify ammonia and nitrites, but does not remove it. If a school is experiencing elevated nitrite readings this product will make it possible to employ larger and more frequent water changes to get the nitrites down; essentially buying time for action on the part of the students or the slow-growing bacteria. The conversion of ammonia to nitrites apparently takes place more quickly than conversion of nitrites to nitrates. You don't want to become overly dependent on a detoxifier, as something has to eventually remove the nitrites, either bacteria or water changes. But it does offer the possibility of saving some fish while either of these techniques or a combination of both are employed.
So what are the take-aways from all of this?
AquaClear filter output very low
Melinda Carpenter, at Bellows Free Academy, sent this message to Bob Wible and Chuck Goller, two of her regional TIC support people.
The water return seems to have slowed down to a dribble. Do either of you have any ideas about how to fix this? Thanks so much!
Chuck responded with:
Have you already checked to make sure the screen over the intake is clean and clear and the intake tube is intact and not clogged? (She had.)
Bob sent this e-mail to Melinda and Chuck:
I have seen a couple of instances where the water leaving the filter has greatly reduced. It was due to either:
1. What Chuck said: a clogged screen at the bottom of the intake tube.
2. An improperly positioned intake tube. Make sure the tube end that connects to the opening in the filter pump is aligned to the hole. Have the pump unplugged and also check that the impeller (which is on that hole) is rotating freely. It could be that something got in there and jammed it.
After an intervention, Melinda reported this:
I did end up taking apart some of the filter after school today and it is much better! I'm not really sure what I did as it didn't seem blocked, but a lot more water is running through, so that is a relief.
Nice work everybody! That's a great example of collaborative problem solving.
Fluval filter not working
Two days ago Poultney Elementary School's Keith Harrington sent me the following e-mail.
I came in today during vacation to check on our trout. The custodians have been feeding them and they look great, however our filter was not running. I took it out. Dumped out the water and started from scratch like it was the beginning of the year. When I put it back in the tank, the motor made a crackling noise for a few seconds and then quit.
The good news is that everything else is running fine and the fish look great. I won't know until we come back on Monday after vacation whether we have funds to replace it. Any advice you have as to how to proceed will be appreciated. I have a beautiful batch and hope I can maintain them.
Keith's school uses a Fluval 406 filter. Two problems that can occur with these are a dead motor or a broken impeller. Because of Keith's description of noise, I suspect the latter. My advice to Keith was to purchase an AquaClear 110 filter either locally or through the Internet. I found the filter available at Amazon for $76.99. (Since I was out of state for a few days, I wasn't able to help him.) Both the Fluval 406 and the AquaClear 110 filters seem equally effective in our TIC set-ups. The AquaClear has three advantages: It's considerably cheaper (the best price I could find on a Fluval this morning was $200); it's easier to set up; and there's almost no danger of a leak that could lead to water on the classroom floor.
Once I'm back in Vermont, I'll pick up Keith's old filter and dive into the process of diagnosing and repairing it. It will either require a new impeller or that I send the motor unit back to the manufacturer. Either way, we'll eventually have a back-up filter available in this area for the next time we have one die mid-season.
Last Saturday, Meg Ritter, of Crossett Brook Middle School, sent me this message and these photos.
Since all of our alevin ended up in the gravel, I built an adaptation of the baster to shoot food to the smaller fry on the bottom. I glued (aquarium cement) a stiff tube to the end of a baster. It seems to have helped and is also helpful to check on those that are resting on the gravel. We squeeze some bubbles towards them--if they move away, they’re fine, if not, or move sluggishly, we pull them out.
Great idea, Meg! I'm sure many teachers will copy you.
The perfect release site
Experienced TIC teachers probably know where they want to release their fish: the place where they released them last year. But new TIC teachers might still be looking for the right location, and even some experienced teachers may realize that there could be an even better site out there. For those still trying to decide where to release their fish, what should be considered?
Remember that Tom Jones of the Vermont Fish and Wildlife Department needs to approve your release site. Normally that is done in the fall as part of the process of requesting eggs. If for some reason you did not request his approval, you can contact him at firstname.lastname@example.org.
Depending on where your school is located, you may have several fabulous release site options close by or you may have no good options without traveling a distance.
What's the perfect release site? I often describe it as "skinny water," a small tributary brook that's just big enough to support trout and the bugs that will sustain them but small enough so that nobody, not even your most over-eager young student, can get into trouble.
Here is my wish list of the ideal characteristics of a great release stream:
What you don't want is a broad, deep stream or river, where kids could get into trouble.
Have a back-up plan too
Another thought: you can't count on the weather, and sometimes on your scheduled Release Day, your first-choice release site is in flood stage. If that's the case, you'll either need to reschedule or go to an alternate site. It's best to start with two dates, your primary date and a back-up "rain date." If that's what you choose to do, make sure that all your helpers have both dates on their schedules.
The other approach is to move up into the watershed of your approved stream. Since water flows downhill--a water table is a great way to demonstrate this to your students--small, high-gradient streams (that means ones that drop steeply and lose altitude quickly) lose the extra water dumped by a heavy rain long before lowland streams do. Streams and rivers in the valleys might still be muddy and dangerously high for days after their tributaries have cleared up and gone back to their banks.
Joe Mark is Lead Facilitator of Vermont's Trout in the Classroom program.
In June 2012, I retired after 40 years in higher education, having spent the last 32 years of my career as dean at Castleton. One of the first things I volunteered to do in retirement was to work with a parent-friend to help the Dorset School, where his kids and my Vermont grandkids attend, start a TIC program. Gradually that commitment grew into my current role, which is both demanding and highly rewarding.