High mortality rate among new fish

[UncleLongHair]

Hi folks, I'm new here, and hope I can get some general advice for my tank.

I've got a 26 gallon freshwater tank that is a big hit in the family, but we seem to have a lot of trouble adding new fish. Of about 10 new fish we've added over the past few months, more than half of them died within the first week or two, some within 24 hours.

Without going into a lot of details just yet, here are the fish we have now:

2 dwarf gourami
2 striped danio
2 neon tetra
2 tiger barb
2 platy
1 gold barb
1 pleco
1 albino cory
1 upside down catfish
2 lamp eye tetra (soon to be 1)

So this is 16 fish in a 26 gallon tank, and most of them are tiny, I think I'm under the "one inch per gallon" rule.

The tank has been running about 3 months, but contains the gravel from a 10 gallon tank that had been running over a year -- when I upgraded from 10 to 26 gallons I moved the gravel and decorations over to try to retain the bacteria, which seems to have worked (zero nitrate and nitrite ever since). The temp holds steady at 78-79F, nitrate and nitrite levels are zero (checked every few days), there is a plate bubbler on the bottom and carbon filter both running 24/7, no salt. Our water is unusually hard but besides that all parameters (nitrate, nitrite, pH, etc) read in the middle of the normal range (according to the scales on the water test kits).

Generally, the fish are happy, they look great, eat great and are peaceful (despite the mixed species). We have only lost 2 fish over about 2 years with no explanation, which I'm guessing is fairly normal. The others we have lost have all been due to new additions, either the new fish died or some old fish got sick when the new ones were added, or both. So obviously I think I'm doing something wrong when adding new fish.

It is very frustrating to buy new fish and find them dead shortly thereafter. I had this experience today which is why I'm writing. We bought 2 lamp eye tetras, and only about 4 hours later, one of them is already looking like he isn't going to make it (sitting on the bottom of the tank gasping). Strangely, the other new guy is fine, as are all of the other fish.

I have tried different things to acclimate new fish, but I can't seem to figure out anything that works reliably. I used to come home and just dump the new fish right into the tank. For over a year I never had a problem with this, and I wondered why people fussed over adding new fish so much. Then one day I did this and apparently introduced ich into the tank which led to the loss of 3 fish including the new one and two old ones.

So I set up our spare 10 gallon tank as as receiving ward for the next new batch. I came home with 5 new fish, floated their bags in the water for about 4-5 hours, then added the fish to the 10 gallon tank, and one of them was dead the next morning (unfortunately my favorite of the bunch, a catfish shark).

Since then, all the other fish are fine (they spent a week in the receiving ward and were later moved into the 26 gallon tank). Today I got 2 new fish, and decided to throw caution to the wind and dump them right into the tank, and one of them is nearly dead a few hours later.

So I guess I have 3 general questions for the folks here:

1) How do you explain the sudden death of one or two fish while the remaining 10-15 fish (new or old, same species or different) are fine? Just bad luck?

2) What is a normal / acceptable mortality rate? Of the probably 30 fish I've bought over the past 2 years, I've probably lost about 8 of them, which I think is kind of high. Generally it seems like new fish die 25-50% of the time, and if they don't die initially, they're good for the long haul.

3) Can I do anything to be more careful when acclimating fish, or is losing many of new fish just par for the course? It is a good thing these fish cost $2-6 each instead of $20-60 like some of the fancier varieties or I'd really be upset. Aside from floating the bag, how can you slowly acclimate the fish to the different water? Unless you come home with a few gallons of the pet store water, you've gotta introduce the new fish to your water within a day or two, so I don't see any other way to go about it.

Thanks very much in advance for any info!

Uncle

 

[JustOneMore20]

Sorry for all your losses. It sounds like the tank should be fine and that water quality (what would normally be my first thought for immediate deaths) is good.

I'm a big fan of drip acclimating fish. When I get new fish, I put them in a small bucket (I have a 1 gallon for this), pour the bag of new fish in, get some regular airline tubing and stretch it from the tank to the bucket. Then, then you start the water flow (easiest way is to suck on the end of the tubing....do it your way though ) and then I tie a knot in the tubing until I slow down the water flow to where it drips. I try to get like a drop a second, but whatever looks slow enough to you will work. I do this for about an hour and I've always had good luck after that with adding fish or shrimp to the tank. This matches the pH and temp (even though the buck may get a little cool near the end of the hour....I've never had issues).

Are you buying fish from the same store each time? If so, it would be worth it to find a different store and try the drip acclimating.

It could be that the pH at the store and yours are very different. Also, by leaving the fish in the bag for 4-5 hours, you match temperature, but the ammonia level can rise in the bag. That and a drastic change in pH could be what killed them, though I'm just guessing about the difference in the pH from the store.


Some of the fish may just be hardier than others and therefore survive while others don't. Or if you are buying from the same place it could be that some fish have health issues and are weak already, so they don't survive the changes.

 

[missileman]

I am confused by your readings.
You say 0 nitrite and 0 nitrate. That is not normal in a cycled 26 gallon tank with 16 fish in it.
You should be reading some nitrate I would be surprised if it was less than 20ppm.In fact in any cycled tank you should read some nitrate.
What about amonia?
PS: you are already past your 1" per gallon rule. You judge it by the adult size of the fish unless you plan on upgrading in the near future.

 

[JustOneMore20]

Oops, I missed the 0 nitrate part and saw:

Our water is unusually hard but besides that all parameters (nitrate, nitrite, pH, etc) read in the middle of the normal range (according to the scales on the water test kits).

I'm gonna agree with missileman that you should have some nitrates in a cycled tank.

Any live plants in the tank? And what kind of tests are you using...strips or liquid test kits? Also, how often do you do water changes? Are you replacing filter media often?

The 1" per gallon rule isn't a good one to follow. I didn't comment on the number of fish you have....but eventually you should decide which schools you'd like to keep and then fill them out (once we get to the bottom of the new fish dying). For now we should figure out why you have no nitrates.

 

[fort384]

I would guess that either you are using an expired test kit, or performing the nitrate test incorrectly. You really have to shake up the reagents well for the nitrate test to get an accurate reading, and the reagents do expire.

A tank that has been around for months with fish in it should have readable nitrates. Are you doing regular partial water changes (not top offs)? What is your ammonia reading?

You should be seeing 0 ammonia, 0 nitrite, and readable nitrates.

 

[UncleLongHair]

Thanks

Wow great thanks for all of the comments! Extremely helpful.

I have some good news about my little lamp eye tetra. Last night his head was buried at the bottom of one of the plants and he was not moving. I thought he was dead, so I reached in with a stick and gently poked him, and was surprised to see him swim wildly for a few seconds and then come to rest at the bottom of the tank, gasping. I figured he was a goner, but this morning he looks fine and is swimming around with his buddy. It is funny, but I think he got stuck! I think he got scared when I put him in the tank and he went to hide and got his head stuck in a plant. Once I poked him he got free and now seems happy.

Thanks for the tip on the "drip acclimation", I have a 1 gallon goldfish bowl I could use for that, I'll use that next time.

Sorry if I was vague about the nitrates and nitrites, you are right, the readings are not zero, more accurately "near zero" or "safe according to the kit". I'm have been using test strips with 5-7 little pads on them. They should be "fresh" as I check the water almost every day due to all of the problems. I checked just now and the nitrates are between 20 and 40 ppm (closer to 40). I guess my point was that they weren't dangerously high at any point over the past few months, and generally I feel that they're under control. Generally they are in the 0-40ppm range, usually around 20.

The kits I've been using don't test for ammonia, I've been relying on the nitrate and nitrite readings. To give you an idea of other parameters, the nitrites are at zero or near to it, pH is about 7.5, and hardness is around 180 (top of the scale).

Generally I've been doing a 5-6 gallon water change every 2 or 3 weeks which includes a thorough vacuuming of the gravel, and I change the filter media about every 4-5 weeks. I think this is a bit on the "lazy" side of maintenance, but so far so good.

No live plants yet, but I intend on adding some once I feel that the tank is well situated. It's tall and thin (21" tall, 14" deep, 24" wide), something tall that waves around would be cool, but I haven't really researched that yet. Any tips or suggestions would be great.

I feed sparingly, maybe one frozen fish cube in the morning (or recently a few tsp of live brine shrimp), a few small pinches of flakes during the day (usually from the kids), and either flakes or half an algae wafer at night. They eat the food in 1-2 minutes and always seem hungry so I don't think I'm over-feeding.

I have bought fish from 3 local stores. I will have to think through it but I think most of the fatalities came from one store. I'm actually a little suspicious of that store, I overheard the owner saying that they bought back stock from some customers, and they recently moved locations and I wonder if the fish got beat up a little. Unfortunately, they have a spectacular selection of fish (the catfish shark was totally cool) so I'd love to figure out if they are safe and how I can get fish from there.

I understand what you mean about the "1 inch per gallon" applying to the fish adult size, and I'm willing to change things around if I'm lucky enough to have all of these guys grow up. I've got the 10 gallon tank where I could move a few of them, and would love nothing more than to upgrade the tank size again, though I'd have to talk my better half into it. But at this rate, through attrition, I should be fine for a couple of years.

I take my kids (age 5 and 3) to the store to pick out the fish so of course we have 1 or 2 of everything. If I were doing it myself I'd probably get a school of one or two kinds of fish to keep it simple, but we have a kind of Noah's Ark thing going...

Uncle

 

[beglely]

I would move the cory, danios, and neons to the ten gallon to save some room. I would also invest in some liquid test kits as everyone here recommends them and says they are more reliable (cheaper than strips too to my surprise). I would also get an ammonia test kit (can get one for about 7 bucks where i live) as that will help you keep an eye on the tank. And if I am correct i read that plants will help reduce your ammonia and nitrate levels in your tank so if you put them in the tank in the future they should help!

 

[fort384]

ok, cool. Your maintenance schedule and water parameters all seem good. I would try drip acclimation and see if that helps solve the problem.

 

[JustOneMore20]

I agree with Fort ^. And maybe steer clear of the suspicious fish store for now and see if you have a better survival rate using just other stores. Atleast then we can rule out that it was sick or weak fish and not necessarily your tank. Drip acclimation should help too.

Your numbers look good (nitrites should always be 0, so hopefully they are). I agree that liquid kits are more reliable, so whenever you can get some (there is a master FW liquid kit made by Aquarium Pharmaceuticals), is fine. Or if you want to stick with what you have, thats fine too...I'd just pick up an ammonia test to be sure that isn't an issue.

Your maintenance looks fine to me too. I was asking about the filter mainly to make sure you weren't changing it too often and causing a mini-cycle, but your schedule is great.

 

[missileman]

The bad part about newly bought fish dying is that you are not sure of what killed them.
If they where sick it is possible that your tank is now contaminated and more fish will follow. Lets hope not.
I bought some fish last year from a big chain store and half died within a week. over the next month more died including long time residents.
After several failed attempts to treat the tank I finally, just by chance, hit on the answer and correct treatment. As it turned out it was internal parasites.
I will never put new fish in anything other than a quarantine tank from now on.