858 The Eighth

Welder Zhao was not a detail-oriented person, and he didn't provide much useful information. He complained repeatedly about how unlucky was. He was half delirious, and just repeated himself over and over. 

Zhang Zian used an excuse to end his conversation with Welder Zhao. 　　

To summarize the information available until now, he suspected that a certain creature in the aquarium tank had caused the massive poisoning incident. He was only 20 to 30 percent sure, however, so he didn't know if he should speak up about it. If he was wrong, he didn't mind being despised, but it would waste their precious time. 　　

Sheng Ke saw that he was thinking about something and asked, "Did you find anything?"　　

"Xiao Zhang, if you found anything, just speak directly. We can't let go of anything suspicious at this moment," Bureau Chief Chen encouraged him.

It was a sunny spring day in March––not too cold or too hot––yet his forehead and Sheng Ke's were full of sweat.　　

The regular police inquired residents nearby to see if there had been anyone suspicious showing up recently. They also pulled out the surveillance recordings of the area. The Biochemical Specialist Police Unit wore thick protective gear and entered Carpenter Wang's residence in groups for a full search. The police and dogs kept the scene secure, waiting for orders at any time. If the Biochemical Specialist Police Unit failed to locate the source of poison, they might have to send the police dogs inside to search for suspicious objects.　　

To make matters worse, the toxin that caused harm was not a common one. All sorts of test papers, reagents, and detectors that the Biochemical Specialist Police Unit brought in were fruitless.　　

Bureau Chief Chen had been talking through a walkie-talkie. The pressure from higher offices had made him exhausted. Despite his troubled mind, he tried to look calm and gentle.　　

Zhang Zian made a brave decision and told Bureau Chief Chen, "Bureau Chief Chen, I suspect that there's something wrong with Carpenter Wang's aquarium tank."　

Sheng Ke and Bureau Chief Chen's faces froze at the same time.　　

"Zhang Zian! You can't joke at this moment!" Sheng Ke told him seriously.　

Bureau Chief Chen paid more attention and asked him, "Are you saying that someone slipped the poison into the fish tank?"　　

"No, not like that." Zhang Zian shook his head. "The fish tank itself was the source of poison."　　

Sheng Ke and Bureau Chief Chen looked at each other, their eyes full of skepticism. Had Zhang Zian not helped the police in a few cases in the past, they would have ignored him completely; they were not in the mood to listen to his nonsense.　　

Zhang Zian knew that the general public didn't know much about aquatic creatures. Even an experienced aquarium owner might not understand it. His words sounded unimaginable to most people. But in fact, some marine creatures were indeed capable of causing such serious harm. 　　

The deep blue sea hid millions of strange creatures beyond human imagination.　　

"Are you saying that some fish in the tank is poisonous?" Bureau Chief Chen asked to confirm.　　

"It might be a fish, or something else. We won't know unless we see it with our own eyes. Otherwise, we can't be sure," Zhang Zian said.　　

It was hard to see it with one's own eyes, as the fish tank was full of water and very heavy. It was hard to carry it downstairs. Besides, if the fish tank was indeed the of source of the poison, then carrying it out without discretion might be dangerous.　　

Bureau Chief Chen frowned and stared at Carpenter Wang's tightly shut windows, weighing the risks against the benefits in his mind.　　

Sheng Ke and Zhang Zian were wise enough not to disturb him.　　

"How sure are you?" Bureau Chief Chen asked after a long time, his face serious.　　

Zhang Zian stretched out three fingers. 30 percent was not a high chance, but it was worth betting for––especially under such clueless circumstances.　　

Bureau Chief Chen stayed silent for a moment, then waved his hand and said, "Prepare a gas mask and protective gear for him."　　

"Bureau Chief Chen, this…" Sheng Ke wanted to challenge him. Involving an unexperienced civilian was too dangerous.　　

"Xiao Zhang, would you like to go inside and try? Of course, it's kind of dangerous," Bureau Chief Chen said, confirming with Zhang Zian.　　

Zhang Zian looked at the police dogs standing by. If he refused, they might have to send the police dogs in, which were far less tolerant than humans. Once they went in, they might never come out.　　

"All right, I'll do it." He nodded in agreement.　　

Sheng Ke saw that he insisted on going in, so he sighed and stopped objecting.　　

The Biochemical Specialist Police Unit brought a full set of protective gear over. They put on protective clothing, a gas mask, and an oxygen tank on him, then explained to him the rules for safety. They also warned him not to run around in the house after he entered.

The weather was cool, but after wearing the thick, protective clothing, his entire body seemed to be covered in a cocoon. It was so hot and humid, and his joints were greatly limited. Unable to look back, he had to turn around if needed. Sounds were muffled and unclear.　　

The special police checked the air pressure for him to make sure it was not leaking. They then gestured him for follow them into the building unit.　　

Zhang Zian walked forward slowly, then turned his body back to look at Bureau Chief Chen and Sheng Ke. He waved at them, his eyes expectant and uneasy.　　

There were no elevators in the old residential building. Each step was exhausting. All he heard was his breath and a slight sizzling of high-pressure gas being released slowly from the oxygen tank. 　　

When they reached the third floor, where Carpenter Wang lived, Zhang Zian was already sweating. Sweat dripped from his cheeks and stuck on his eyebrows. His face was so itchy, but he couldn't scratch it, which made it itch even more. 　　

He forced himself to focus on Carpenter Wang's apartment.　　

There were a lot of shiny pieces of equipment at the door. The Biochemical Specialist Police Unit was busy analyzing and moving things. They were surprised to see Zhang Zian's strange face, and they asked through the microphone, "Who is this? Expert from the provincial office?"　　

"No, he's not police. He is… someone Bureau Chief Chen sent for help," the person that brought Zhang Zian upstairs explained.　　

"For help?" The specialist lead's tone was full of doubt. But since Bureau Chief Chen sent him, he couldn't say anything further. Maybe Zian person had something special in him. "What do you suggest?"　　

Zhang Zian saw the fish tank in the living room corner right away.　　

In fact, judging from the location of the fish tank, Carpenter Wang was much more experienced than Welder Zhao and Electrician Wu. The corner was shaded and away from direct sunlight all day. A bright metal-halide lamp was placed 30 centimeters above the tank, with LED lights next to it to balance the light spectrum. The entire tank relied on artificial lights. 　　

"I'll check out the fish tank." He pointed at the fish tank and said, "I think the source of poison is in the tank."　　

"In the tank? We've examined the tank. There's nothing unusual." The specialist lead shook his head.　　

As the toxin was rare and unknown, common test papers, reagents, and detectors were not working. The Biochemical Specialist Police Unit had to consider all possibilities, including potential radioactive substances hidden somewhere indoors.　　

"Maybe it's invisible," Zhang Zian said. As nobody was objecting, he moved his steps slowly towards the fish tank.　　

The water was clear in the tank, and everything was visible. A few dead fish floated on the surface. Beautiful corals attached themselves to the live rocks. The tank was presentable in both aquascaping and coral maintenance.

Usually, fish and corals should not be put together immediately after restarting a tank. Maybe Carpenter Wang felt sick when he was only half done. He gave Welder Zhao a few random fish to send him away.

The specialist lead didn't want him to get out of his watch, since he didn't know if he would touch something dangerous. He followed him and asked, "Do you think these fish are problematic? Even if the fish are toxic, they should not poison themselves, should they?"　　

Clearly, apart from the fish, there was nothing else that could move in the fish tank. Besides, according to common sense, no fish could be that toxic.　　

Zhang Zian said, "Come, help me out. Scoop some of the water out of the fish tank, then take out all of these rocks. Be careful! The tank water may be highly toxic. Don't dump it into the sewer!"　　

As everyone was wearing heavy protective gear, and the tank was massive, it was very hard to remove the rocks without scooping the water out.　　

The specialists were not very willing to follow the civilian's instructions. They agreed to help reluctantly after they asked Bureau Chief Chen. They used every single container they could find in the apartment and scooped out about half of the water. 　　

Then, the rocks were taken out one after another and placed on a waterproof canvas.　

Zhang Zian started examining the corals attached to each live rock they took out. All the corals were common species, however, so they could not be the culprit.　　

The photographer specialist took photos of the rocks attentively, while someone else took care of the filming.　　

The fish tank was empty. Apart from the sand stirred up on the bottom, there was nothing else.　　

Everybody stared at Zhang Zian, as if to ask, "What now? We told you there was nothing unusual in the fish tank."　

Zhang Zian fixated his eyes on the last live rock. There were some brown and negligible umbrella corals attached to it. They had radiating stripes on top, and a circle of gently wriggling tentacles growing evenly on the umbrella's edge. 　　

As the tank was placed next to the wall, the live rock on which the brown corals were attached to was leaning on the wall. They could be ignored easily, as they were not visible from the front. 　　

He was almost certain that Carpenter Wang didn't realize the brown corals were growing in his tank, as they were very ugly. Nobody would be willing to buy them.　　

Zhang Zian could not guess whether Carpenter Wang had seen the hidden corals last night while he restarted his tank, or if he tried to get rid of them or not. Anyway, they got very upset.　　

He was relieved, then pointed at the brown corals and said, "Here they are––the source of poison you are looking for."　　

Commonly, creatures with brighter colors were more likely to be dangerous. Creatures lacking vibrant colors were more likely to be safe.　　

"What are these? Corals?" the specialists asked skeptically. "Are you sure?"　　

Zhang Zian nodded and said, "These are Palythoa corals. Don't look down upon them. They can release a toxin called Palytoxin, ranking them number eight on the world's most toxic substance list. The top seven toxins include Botulinum toxin, radioactive Plutonium-210, Diphtheria toxin, and so forth. 21 milligrams of Palytoxin is enough to kill an adult weighing 70 kilograms to 21 milligrams! The unit is not grams, but milligram, or 0.000021 grams."　　

Then he pointed at the very bright metal-halide lamp that radiated high heat above the tank. "These corals sensed danger, and they released their toxin into the water. It killed the other creatures in the tank first, then the toxic saltwater evaporated into the air under the metal-halide lamp. Carpenter Wang family inhaled it, then Welder Zhao and the other firemen. This caused the poisoning."　　

In the most toxic creatures list often seen online, Palythoa corals were never included. But the Palytoxin they released was dozens of times more toxic than the notorious blue-ringed octopus and cone snail. Plus, there was no cure. Inhaling a trace amount would lead to acute poisoning.　　

In fact, Palytoxin poisoning incidents had happened before in aquarium owners. The dangerous corals usually slipped into the tank by attaching themselves to live rocks, and grew they up slowly. If they sensed danger, they would release the toxin.

If Carpenter Wang didn't use a metal-halide lamp, the salt water would evaporate more slowly, and the poisoning would be less severe. The lamps were too hot, much like a small burning sun.　　

The biochemical specialists were very experienced in handling dangerous substances, but it was their first time hearing about such horrifying corals. They were too shocked to speak.　　

"Reporting to Bureau Chief Chen! The source has been located. It's…" The team lead reported to Bureau Chief Chen via walkie-talkie. He glanced at Zhang Zian and said, "It's the corals in the fish tank."　　

"What? Repeat!" Bureau Chief Chen could not believe his ears, thinking he made a mistake. After all the fuss, the culprit turned out to be corals?　　

"Not a common type of coral, but a very toxic type, called Palythoa corals." The team lead explained the best he could.　

Bureau Chief Chen was both astonished and greatly relieved. The source of poison was located, no matter what. They could now send the experts from the provincial office home. At the same time, the nature of the incident had changed radically.　　

He continued to ask, "Is there a possibility of intentional poisoning?"　　

The team lead was unable to answer his question. He hinted to Zhang Zian to answer it.

"Reporting to Bureau Chief Chen. I don't think it's intentional," Zhang Zian said. "It most likely came from the live rocks that Carpenter Wang bought."　　

"Live rocks? Where did he buy the live rocks?" Bureau Chief Chen gave a serious order, "Find out where he bought the live rocks, then search that shop. How can anyone trade such dangerous creatures?"　　

Zhang Zian felt sorry in his heart. It seemed that the aquarium that sold Carpenter Wang the live rocks was in big trouble. They might not be able to run their shop anymore after being nvolved in such a big incident.　　

"Bureau Chief Chen, please instruct how to dispose of these corals," the team lead requested.

Bureau Chief Chen thought for a while and said, "Seal them up and bring them to the office first. Be careful."　　

The specialists sealed up and preserved the live rocks and the corals with great care.　

Zhang Zian was free now. He walked downstairs by himself, then took off the gas mask at the unit door, letting his sweaty face dry in the breeze.　　

"Xiao Zhang, this is really impressive!" Sheng Ke walked up in excitement.　　

"I'm glad the mission is accomplished," Zhang Zian said, smiling.