Tropical Fish Keeping - Aquarium fish care and resources

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Tomm1986 08-28-2013 05:52 PM

Dead fish :-(
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Hi all

I hope someone can help with my question.
I used to keep tropical fish around 10 years ago, I had guppies, plecos, a siamese figher and neon tetra. It was a pretty cool aquarium but I gave it up when I moved house with my parents.

In April I got myself a new 80 litre aquarium with a built in filter, a photo of the tank is attached. The light doesn't work and I had to buy a heater but apart from that it's perfectly fine.

To bed the tank in I bought 2 gourami,2 mollies and 2 nano shrimp around the middle of May. The tank had been running for around a month and I had water tests done at my local pets at home store- nothing was wrong and they were happy for me to go ahead and start the tank off.

Things seemed to be going fine so after a while I bought 4 Neon Tetra, 1 Siamese Fighter, 2 more nano shrimp and a pleco.

The pleco died about 3 days after I bought him, put it down to stress and was offered a replacement as they tested the water again and nothing was wrong. I bought 4 more neon tetra and a further pleco to keep the replacement company, all plecos have been about 6cm long when I bought them.

A neon died last week however I thought this was due to stress again and wrote it off.

I've come home from work today to find both plecos dead, all but one Neon (6) dead and one molly dead.

I've done an instant water change in case it was due to anything in the water so I may prolong those which are left. There's a few bit of flakes left at the bottom as a result of changing fish food (I've changed from an expensive brand to Aldi Fish Flakes and they don't seem as keen on this!).

I know that excess food can result in ammonia spiking, however surely it would take a lot to kill so many in such a large tank?

I'm going to pets at home tomorrow with the dead fish and a water sample in a separate container (to prevent overnight nitrate spikes in the water bottle due to the dead bodies) to see what they suggest, however I know that they may not know everything.

I'm distraught and wonder if anyone here has ever faced something like this and if they can suggest anything for me?



JDM 08-28-2013 08:12 PM


Originally Posted by Tomm1986 (Post 2901977)
new 80 litre aquarium

2 gourami,
2 mollies
2 nano shrimp around the middle of May. The tank had been running for around a month and I had water tests done at my local pets at home store- nothing was wrong and they were happy for me to go ahead and start the tank off.

4 Neon Tetra
1 Siamese Fighter
2 more nano shrimp
a pleco.

4 more neon tetra
a further pleco
all plecos have been about 6cm long when I bought them.

I've changed from an expensive brand to Aldi Fish Flakes and they don't seem as keen on this!

I know that excess food can result in ammonia spiking, however surely it would take a lot to kill so many in such a large tank?


Sorry to hear that you are losing so many fish.

First, you really need to get your own test kit. API master test kit (liquid test) is popular as it tests ammonia, nitrite, nitrate and pH. GH and KH can be had in a separate kit or just get the numbers from the water supply if you are on town water. The store saying everything is fine can be misleading as they really are in the business of selling fish.

80 litres is about 20 gallons, less seeing as you don't have the tank full. That's a lot of fish to stock so quickly in that size of tank. The plecos, at 6cm, are already almost 2.5 inches, they are too much for a small tank. I had one in a 20 gallon that I had to return to the store (after many years of someone else looking after the tank, he had severely outgrown it long ago).

I might suspect the fighter killing the fish as well. I have a Betta in my tank with barbs and cats but I added them over time and watched them very closely, bettas are more typically aggressive and should not be kept in a community tank if given the option. I would have chosen otherwise as it severely restricts fish selection but it was my daughter's fish and he was going in the big tank first.

Separate unrelated point, don't cheap out in the fish food. Stick with quality foods that aren't full of fillers like wheat and other non-fish related stuff. Any food goes a long way for the buck so it isn't really that much over time if not over feeding.

Once you have tested the water yourself you will have a better idea of what may be going on in there if it is water related.


moghedan 08-29-2013 12:05 PM

Sorry to hear you lost so much.

Do you have a thermometer? Check your heater.

The betta and gourami surviving might be the clue that points to the water being too hot or not enough oxygen in the water. Too cold for the tropicals is also possible, but that usually doesn't get a molly immediately; usually you get the "Shimmies" for at least several hours. Heater getting the water to 90ish will do EXACTLY what you described.

Before you Restock:

Neons are strange little fish. Generally, they are fairly hardy, but they have a nasty habit of dying quickly and without apparent reason in tanks that that less that six months to a year since setup. I do not have a clue why, and not everyone has the problem, but it is common enough to be worth mentioning.

Harlequin Rasboras are commonly available fish that enjoy the same water as Neons, dispite being from opposite sides of the planet. They are colorful and active, and make good tankmates. Some people use them to keep a tank from becoming boring until it is mature enough for neons.

Pleco can mean a lot of things... first, you have to know what species it is. Plecos also have a fairly large number of requirements for survival... and most are solitary loners. Keeping plecos is great if you want to keep plecos. If you are looking to throw in a fish to take care of algae, they aren't the best choice. Read More here:
Pleco, Plecostomus, Hypostomus plecostomu Catfish Guide

Bettas are... individuals. People that swim, if you will. Each has a very distinct personality. Some are more passive, others more aggressive. Keeping a Betta with friends is delicate balance of that personality and the actions of your other fish. Generally, they will flare at anything bright and colorful, like a school of neons or a male guppy. While they might want to kill a Neon, Neons are very fast fish, and Bettas are very slow. For all the hype of the aggressive Betta, the most common issue with Bettas in a community tank is the Betta being harassed and fin nipped.

The gourami are the next problem. It is generally considered unwise to keep anabantids together. Some people have managed it, but they usually need a large tank to do so. Read more here:
Labyrinth Fish, Guides for Betta, Gourami and Paradise Fish

Tomm1986 08-29-2013 01:44 PM

Thank you both for your comments, they were of great help - the links in particular were extremely interesting.

I forgot to mention in my distress last night that my 3 zebra danio also survived which I was extremely happy to see.

I went with my water today to get it tested and found:
  • PH was at 6.0, was told this would account for the plecos (bristle-nosed) dying despite being quite hardy;
  • the Ammonia is between 0.5-2.0ppm;
  • Nitrite between 0.25-2.0ppm;
  • Nitrate is between 40-160ppm
Was told the Ammonia and Nitrite levels were verging on toxic for the entire tank and to change 25% water today with another 25% tomorrow (of course using tapsafe). Once the ammonia and nitrate is down I was then told to increase PH on Saturday - slowly. Apparently increasing straight to 7 would shock the rest of the fish and kill them?

I've also bought a gravel cleaner to get rid of all the excess food, got to be careful not to suck the shrimps up too...

What do people think about this course of action - is this best way to go ahead?

I think the high buildup was due to overfeeding (the mollys always were looking for more food!) The neons were said to be the aquarium version of canaries - anything changes for the worse and they are the first to go.

Am puzzled why only one of the mollys survived though, it's my favourite out of the two so I'm very thankful.

Re: the fighter, he's quite happy (and slow), I've not seen him going after any of the neons before but I'll definitely keep an eye on him for a while.

I did check the temperature last night and it was on 23/24 so I turned it up to 24/25.

The Gourami and Fighter seem to be getting on relatively ok, it's a big tank with lots of plants and bogwood and haven't seen any fights (yet), but I'll definitely bear this in mind and limit my gourami to two.

I had planned to go for another pleco when I restock as I do love them (I love looking at them when they're up against the glass), they're peaceful and they're (meant to be) hardy too. What would your suggestions be for something else instead?

My ideal would be to restock the neons to about 10/12 and add to the zebra danio to have about 8 before bringing another pleco in. Keep the rest as they are but bring in more plants and bogwood for hiding places.

Is this realistic? Can anyone see any problems with that sort of setup?



JDM 08-29-2013 02:29 PM

All the toxins are quite high and need to come down. With the pH near 6.0 the ammonia is not so much of a concern (ammonia / ammonium ratio changes with the pH making it more toxic with higher pH levels) but nitrites and nitrates are. This is where having your own test kit is an advantage, test your source water so you know what it is at.

If it were me and the source parameters were close to the tank water parameters, I'd do a larger change, as much as 75% but smaller frequent changes might be better if the tank water is "old".... 2 25% changes won't do it though, keep changing it until the tank stabilizes as it is not up to the task of handling your current stocking levels (which may have a lot to do with the debris on the bottom decomposing and adding ammonia in addition to the fish production) Only consider adding more fish after this which might take a month... but it takes as long as it takes. The ideal time is after the ammonia reads zero and the nitrite reads zero consistently and your water changing schedule is keeping the nitrates as low as possible, aim for 10ppm or less.

Don't mess with the pH, artificially adjusting the pH will lead to heartache as it is only temporary and will cause pH swings that are worse for the fish than a steady slightly out of range pH. This gets back to knowing your water source parameters. If the source pH is higher then it will adjust as you start using more source water regularly.

The ideal is to keep fish that fit your water rather than attempting to alter the water to accommodate the fish.


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