Unexplained losses..

[arelldee]

I have a 180 litre community tank, established about 18 months now and am having a problem with fish dying unexpectedly.

Water parameters are pretty constant, pH 7.5, Ammonia/Nitrite levels at or very near zero, Nitrate levels at 30-50 mg/L (ambient tap water around here about 30 mg/L), changing 30-35% water every week or two. Filtration appears fine and new media introduced as required or suggested by filter manufacturer.

However, over the last 10-12 weeks individual fish have died intermittently, one or two perishing every week or so but none altogether , no one species or none of similar symptoms. Symptoms have included swollen abdomen, buoyancy problems, one or two external growths/ulcers, some loss of colour and, in some cases, a strange "arching" malady where the fishes back appears hunched. Have treated for internal bacterial infection, running two courses of treatment, one initially and the other about two weeks ago. Things appeared to have settled down but have lost two fish this week. No new fish have been introduced for at least six months.

Current stock: 2x Golden-wonder panchax, 2x keyhole cichlid, 5x peppered corys, 1x corydoras julii, 4x neon tetra, 2x cardinal tetra, 2x rosy tetra, 3x bleeding heart tetra, 1x pentazona barb, 1x bumblebee goby, 3x gold algae eater, 2x ottocinclus, 1x platy, 5x white cloud mountain minnow, 4x glowlight tetra, 2x blue tetra, 2x pretty tetra

Anybody got any ideas?

 

[Angel Lady]

Hi and welcome to the forum, sorry to hear about your bad luck what kind of medicine are you using in your tank right now? What kind of filters are you using on your tank?

 

[CFC]

Current stock: 2x Golden-wonder panchax, 2x keyhole cichlid, 5x peppered corys, 1x corydoras julii, 4x neon tetra, 2x cardinal tetra, 2x rosy tetra, 3x bleeding heart tetra, 1x pentazona barb, 1x bumblebee goby, 3x gold algae eater, 2x ottocinclus, 1x platy, 5x white cloud mountain minnow, 4x glowlight tetra, 2x blue tetra, 2x pretty tetra

Anybody got any ideas?

For a start you are well overstocked for a 180L (roughly 40 to 45 gallons ) you should have no more than 50 inches of fish (adult sizes )in that tank at the very most and i counted up to 80 inches even when being conservative with some of the adult sizes !

Also the compatabillity of some of the fish is a definate no no,Golden wonder panchax are predators that will kill and eat tetras,trust me i know i have one that used to beat on my snakehead ! They are not a fish for the small fish community tank.
Bumblebee gobies are brackish fish (meaning they need quite a lot of salt in the water ) and should only be kept in brackish water with other small brackish species.
Gold algea eaters are otherwise known as gold sucking loaches,they are territorial and aggressive,while they will be ok with tetras and other tiny fish they will attack any fish they feel is a threat to their space,there is no way you can keep 3 in one tank (unless the tank was 200 gallons plus) without them fighting.
Pentazona barbs are shoaling fish that need to be kepy in groups of at least 4 to feel secure,kept singlularly they will be aggressive and more prone to disease.

If you bought all these fish from one store then the sales person needs shooting,anyone who knows anything about fish should have told you some of your fish were incompatable.You need to remove at least 30" of fish or buy a bigger tank asap before you have even more problems.I know it sounds harsh but 180L is quite a small tank still and can only hold relatively few fish.

 

[arelldee]

Fish guru - further info; the filter is an external Rena Filstar xP2 and was bought with the tank set-up and is said to cope with tank sizes 150-300 litres. The treatments used were Interpet #9 - Anti Internal Bacteria, dosages and instructions followed to the letter.

Re-stocking levels; "expert" opinions differ depending on who you read/listen to. The factor here would seem to be availability of oxygen in the water and surface area into which atmospheric oxygen can dissolve and/or the use of additional oxygenating methods. Even if you accept that stocking levels are towards the maximum sustainable, they have been so for 12 months at least and the fatalities have occurred only relatively recently. If oxygen scarcity is to blame, wholly or in part, then other factors must be affecting dissolved O2 concentration in the water. Waste related toxins seem to be within normal tolerances.

Re fish compatability; agree that mix is not ideal rather than incompatible and is the result of some poor advice when stocking initially, mis-selling of species and an unfortunate inheritance. However, tank relations between inmates appears cordial. GW Panchax are insectivorous in the wild, hence their surface dwelling nature, are well fed on mosquito larvae and have not as yet shown any aggressiveness towards other species in the tank. The gold sucking loaches have established territories and only clash on the ocassional border dispute. Bumblebee goby has survived in my freshwater tank for a year and in its previous freshwater home for some time before that. P Barbs were in a school of four but have suffered most recently. Again, fish incompatability would not seem to explain recent fatalities.

 

[CFC]

It would seem that low oxygen would be the problem here then. Since you mention the interpet range of treatments i presume you are in the UK ? With the recent hot weather weve been having the oxygen levels would have plummeted ( unless you have a chiller unit on the tank or air conditioning in the room ) the use of the treatment would have only made things worse, lowering the oxygen levels even further. Although it may have not killed the fish directly it would have stressed the fish considerably, lowering their immunity and leaving them open to all kinds of infections. The fact that you mention that the barbs have suffered the worst confirms this to me as barbs are always the first fish in a community to suffer from low oxygen levels, due to the fact that they usually come from the cooler tropical areas.
If you are not already i would sugest the use of a airstone in the tank and turning any flow provided by powerheads/filter outlets towards the surface ( if possible ) to provide as much surface aggitation as possible.

 

[arelldee]

Have had a pump and an air-stone for a while and increased the flow when I started the first course of treatment and, together with the increased frequency of water changes, thought this would suffice.

Cooler weather and things already in hand, such as air stone and frequent water changes should correct any oxygen deficiency. Are oxygenating tablets effective?

 

[Alien Anna]

Have had a pump and an air-stone for a while and increased the flow when I started the first course of treatment and, together with the increased frequency of water changes, thought this would suffice.

Cooler weather and things already in hand, such as air stone and frequent water changes should correct any oxygen deficiency. Are oxygenating tablets effective?

The oxygen carrying capacity of water is a direct function of it's temperature - rather like the way hot tea dissolved more sugar than cold. It doesn't matter how many air-stones etc. you chuck in there, only so much oxygen can be absorbed.

Additionally, many medications you add to the tank also serve to reduce the oxygen-carrying capacity of the water, so you may have been in a Catch-22 situation.

As you are heavily stocked and we have had the worst heatwave since records began, there is a fairly high chance that oxygen deprivation was the root cause of the problem. I too have lost stock because of it Hopefully the cooler weather will mean that we can all relax a little.

 

[wetwetwet]

Hi arelldee

I presume your tank did suffer in the hot weather.... - what temps did you get up to?

...but also with a lack of O2 i'd have thought you'd see faster breathing/gasping at the surface or more trips to the surface.....

With an established tank and good maintenance schedule/WCs I cann't see a problem with working on 2" of fish per gallon (UK).....jmho

As anna says if the probs were down to the heat wave then we can all relax a little

 

[arelldee]

No noticeable gasping or more trips to the surface but then again I only get to watch the tank in the evenings when I get home from work....cooler by then. Water temperature has been hitting 28/29c.

Lost a neon and a rosy tetra over the weekend, they had both been looking off-colour for a week or so and I'm hoping that this is the tail-end of the problem and that the cooler weather will see the tank settle down again. I have heard that people have kept their tanks cool by immersing sealed glass bottles of chilled water into them....does this help/work or cause problems of its own?

My stocking levels have been pretty steady for quite a while and the set-up had been stable until the recent period so it would appear that, in the absence of hot weather and treatments, it can sustain the population at this level. Have been using just under the ratio you suggest WetWetWet, namely 2" per (imperial) gallon.

 

[Alien Anna]

I keep my tanks cooler in summer by floating cooler box ice blocks on the surface. I keep changing the ice blocks (I have about 8 in the freezer) every couple of hours. It takes the edge off the temperature, keeping it below 86F, but isn't all that effective long-term.

The only thing I've been told definitely not to do is add cold water - the sudden shock could kill the fish.